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Home » Recipes

Unaju (Japanese Grilled Eel on Rice)

Published: Jul 30, 2023 · Modified: Sep 17, 2023 by Yuto Omura

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Learn how to make delicious restaurant-style unaju at home! Made with tender pieces of grilled eel coated in a sweet, homemade unagi sauce and served over rice in a special box called "jubako", this luxurious dish is sure to impress!

grilled eel coated with homemade unagi sauce and sprinkled with sansho pepper served over rice in a black lacquerware box (unaju) with a plate of pickles and bowl of clear soup

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Jump to:
  • What is Unaju?
  • What is Jubako? An Essential Element of Unaju
  • Ingredients and Substitution Ideas
  • Step-by-Step Process
  • Storage Options
  • Unaju (Japanese Grilled Eel on Rice)
  • FAQ

What is Unaju?

Unaju or unajyu (鰻重) is a Japanese dish of grilled eel served with special eel sauce and freshly cooked Japanese rice in a special stacked box called jubako (重箱). The jubako in which it is served lends it's name to the dish, with "unaju" being a combination of the words "unagi" (eel) and "jubako".

At Japanese restaurants that specialize in eel dishes, the two most popular menu items are unadon (a grilled eel rice bowl) and unaju (grilled eel served on rice in a box). Interestingly, there is no difference in the taste or quality of the eel between the two dishes. The only difference lies in the vessel in which the rice and eel are served.

If it's in a bowl, it's unadon; if it's in a stacked box, it's unaju. However, unaju is often a higher-graded menu item with more eel, eel liver soup (kimosui), and a small bowl of side dishes.

To learn more about the history of eel in Japan, its varieties, and why it is a luxury food, please see my unagi donburi article.

grilled eel coated with homemade unagi sauce and sprinkled with sansho pepper served over rice in a black lacquerware box (unaju) with a plate of pickles and bowl of clear soup

What is Jubako? An Essential Element of Unaju

Earlier, I mentioned that if you want to prepare unaju instead of una don, you will need a box called jubako (stacked boxes). This is a container used to serve food and has a lid. It has been used in Japan since old times and can be considered a traditional storage container.

The history of this container can be traced back to the Muromachi period (1333-1573), and it is said to have been widely used from the late Edo period (1603-1868) to the early Meiji period (1868-1912). The main shapes are square or circular, and although lacquer ware was traditionally used, various materials, including plastic or wood, are now used. The number of shelves is usually four, representing the four seasons, but there are also two, three, and five variations.

However, most stacked boxes for unaju are sold with only one shelf, and the size is smaller than those for osechi or lunch boxes. Different colors are also available, some in black and others in vermilion. Buying a jubako solely for making unaju at home can be expensive, so I personally suggest making unadon instead if you don't want to buy jubako, as the contents are the same.

grilled eel coated with homemade unagi sauce and sprinkled with sansho pepper served over rice in a black lacquerware box (unaju) with a plate of pickles and bowl of clear soup

Ingredients and Substitution Ideas

  • Fresh eels - If you live in an area where fresh eel is available, I definitely recommend getting fresh eel! However, if you cannot get eels at all, pangasius, catfish, and conger eel are popular substitutes.
  • Turbinado sugar - Coarse, hard, light brown-colored sugar, known as "zarame (ザラメ)" in Japan. It is used to make a more decadent eel sauce than regular sugar. If you cannot find it, please substitute light brown or regular white sugar.
  • Dark brown sugar - Use a small amount to add extra richness. I like to use muscovado sugar, but you can use any other brown sugar or the same sugar as before.
  • Sake - I usually recommend substituting white wine or dry sherry for smaller quantities, but in this case I do not recommend substituting sake for anything else because it is a very important ingredient in eel sauce.
  • Mirin - When purchasing mirin, it is recommended to look for "hon mirin" (本みりん) for the best flavor. I recommend Hinode Hon Mirin as a high-quality and affordable option. See my 20 Most Useful Condiments and Seasonings for Japanese Cooking post for more recommendations.
  • Soy sauce - If you are looking for something reasonably priced, you can't go wrong with Kikkoman soy sauce. Please see our guide to soy sauce article to learn more about how to choose soy sauce in Japanese cuisine.
  • Cooked Japanese short-grain rice - Short-grain Japanese rice is best used for donburi dishes. Recommended Japanese rice available in the U.S. and how to cook Japanese rice in a pot are explained in the How to Cook Japanese Rice Recipe.
  • Japanese pepper (optional) - Known as "sansho" in Japan, this pepper has a distinctive spicy flavor. Even Japanese people have different likes and dislikes, but I personally believe grilled eel is incomplete without sansho. If you want to try it, you can purchase S&B sansho pepper that I used from Amazon.
Japanese Pantry Ideas

I have listed my recommended Japanese condiments, tools, and ingredients in the Sudachi Recipes Amazon shop. If you want to keep making various Japanese foods at home, please check it out!

grilled eel coated with homemade unagi sauce and sprinkled with sansho pepper served over rice in a black lacquerware box (unaju) with a plate of pickles and bowl of clear soup

Step-by-Step Process

Here are my step by step instructions for how to make restaurant-style unaju at home. For ingredient quantities and simplified instructions, scroll down for the printable recipe card.

STEP
Prepare the unagi sauce

Add the turbinado sugar and dark brown sugar to a small saucepan and heat on medium-high.

turbinado sugar and dark brown sugar in a pan to make unagi sauce

Once the sugar starts to melt, add sake and mirin and bring the mixture to a boil. Cook for 2 minutes and stir occasionally to prevent burning.

melted sugar, mirin and sake in a sauce pan to make unagi sauce

Lower the heat to a simmer and add the soy sauce. If you want a deeper unagi flavor, add the head and bones from the unagi to the sauce.

unagi sauce with eel heads and bones

Simmer for about 10 minutes and stir occasionally to make sure it doesn't burn. Once it's thick and syrupy, remove the pan from the heat. (If you used the head and bones of the eel in the sauce, pour the sauce through a sieve to remove them and discard.)

STEP
Wash and cut fresh eels
eels being cut on a plastic wrap

First, wash the surface of the eel in cold water and dry the surface with kitchen paper.

Cutting eels can be a tricky task due to their slippery texture. To avoid any accidents, it's important to cut them in a specific way. A helpful tip is to use plastic wrap to make the cutting process smoother.

Rather than moving the knife, hold it still and move the eel back and forth underneath it. Depending on the size of the eel, it may need to be cut into 2 or 3 pieces. For instance, I cut two large eels into six fillets. Don't forget to wash the eels under cold running water beforehand.

STEP
Steam with sake
steaming eels in a frying pan

One way to make eels extra tender, fluffy, and soft is to steam them before grilling, a common practice in the Kanto region of Eastern Japan. In contrast, the Kansai style involves grilling eels directly.

It is believed that steaming eels before grilling helps remove excess fat, which is more prevalent in eels from the Kanto region compared to those from Kansai. Ideally, a steamer should be used for this process, but if unavailable, steaming the eels with sake on medium-low heat for five minutes can be a simplified alternative. I could hardly believe how melt-in-your-mouth the eel becomes at the end, so I highly recommend this step!

STEP
Grilling unagi in broiler
grilling unagi eel on a home grill

This recipe is designed for those who wish to prepare unaju at home rather than grilling unagi at a BBQ. But if you want to cook over BBQ or charcoal, turning it over early is essential to prevent the meat from easily burning.

In the case of using a broiler, we will use a lot of sauce for this recipe and recommend lining the grill with aluminum foil. Preheating the grill for 5 minutes before placing the eel inside is crucial.

Although the general rule of thumb is to grill fish skin side up, I suggest placing the skin side down for eel as it tends to shrink quickly. This helps prevent the fish from breaking apart.

STEP
Turn them over
flipping unagi eels over on a grill

After six minutes, turn the eels over and return them to the grill. Grill them for an additional five minutes using the same setting.

STEP
Generously brush the sauce
Applying unagi sauce on eels on skin side

After grilling the eels, we add sauce to them. This stage is known as shirayaki (白焼き) when the eel is grilled without sauce. To ensure the sauce penetrates the eels, we repeat the process of applying the sauce several times.

We generously apply the sauce onto the surface of the eels using a brush. Once coated, we put them back onto the grill and cook for 1 minute on high.

Adjust the heat and time for those cooking on a barbecue to avoid burning too much.

STEP
Turn them over and repeat
applying unagi sauce on meat side on a grill

Once 1 minute has passed, flip the fillets over and coat the skin side with sauce again. Return the meat to the grill for another 1 minute. Repeat this process for two more rounds.

STEP
Brush the sauce on rice

Place a layer of cooked rice in a stacked box and brush the eel sauce on top of it.

rice in a lacquerware box brushed with unagi (kabayaki) sauce
STEP
Assemble

Place the eels and top with sansho pepper and leftover eel sauce to taste!

grilled eel coated with homemade unagi sauce and shansho pepper over rice in a black lacquerware box

Finally, enjoy your restaurant-style unaju cooked from scratch!

Storage Options

If you use fresh eels, it is not advisable to freeze them as is. Freezing them will cause a loss in quality of both texture and taste. Since eels are high-quality and expensive fish, it is best to avoid storing them this way.

If you bought too many eels, I would recommend cooking all of them until they reach the shirayaki stage (cooked, but without sauce). Frozen shirayaki eel can be kept for up to a month.

When you defrost shirayaki eel, it is best to place it in the refrigerator beforehand and allow it to defrost gradually instead of rushing it using the microwave straight. Afterward, you can steam them in a pan with sake or lightly grill them in the oven or on the grill. Steaming the meat will result in a fluffier texture, while grilling or using the oven will make for a crispier exterior.

breaking unagi in unaju with black chopsticks

I hope you enjoy this homemade unaju recipe! If you try it out, I'd really appreciate it if you could spare a moment to let me know what you thought by giving a review and star rating in the comments below. It's also helpful to share any adjustments you made to the recipe with our other readers. Thank you!

grilled eel coated with homemade unagi sauce and sprinkled with sansho pepper served over rice in a black lacquerware box (unaju) with a plate of pickles and bowl of clear soup

Unaju (Japanese Grilled Eel on Rice)

Yuto Omura
How to make delicious restaurant-style "Unaju" with grilled eel, and amazing homemade unagi sauce served in a special box called a "jubako". (Recipe doesn't include cooking rice.)
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Prep Time 20 minutes mins
Cook Time 35 minutes mins
Total Time 50 minutes mins
Course Lunch, Main Course
Cuisine Japanese
Servings 2 portions

Ingredients
 
 

Unagi Sauce

  • 3 tbsp turbinado sugar - (zarame) light brown with coarse texture
  • 1 tsp dark brown sugar
  • 75 ml sake
  • 75 ml mirin
  • 75 ml soy sauce

Unagi don

  • 300 g filleted eels - 1 fillet is approx 150g
  • 2 tbsp sake
  • 2 portions cooked Japanese short-grain rice - see here for how to cook Japanese rice
  • Japanese pepper (sansho) - optional
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Instructions
 

Unagi Sauce

  • Take a small sauce pan and add 3 tbsp turbinado sugar and 1 tsp dark brown sugar. Place the pan on the stove over a medium-high heat.
    turbinado sugar and dark brown sugar in a pan to make unagi sauce
  • When the sugar begins to melt, add 75 ml sake and 75 ml mirin. Boil for 1 to 2 minutes, stirring occasionally to evenly distribute the heat.
    melted sugar, mirin and sake in a sauce pan to make unagi sauce
  • Lower the heat to a simmer and add 75 ml soy sauce. If you want to add extra depth to your sauce, add the bones and heads from the eels.
    adding soy sauce to pan to make unagi sauce
  • Simmer for about 10 minutes or until thickened to a syrup-like consistency. Stir occasionally to prevent the sugar from burning.
    unagi sauce with eel heads and bones
  • Remove from the heat and allow to cool while preparing the eel. (If you added the bones and heads, pour through a strainer and discard.)

Unaju

  • Wash 300 g filleted eels under cold running water and pat them dry with kitchen paper.
  • Lay a sheet of plastic wrap over a chopping board and place the eel on top. Cut into halves or thirds by gently pressing a sharp knife into the area you want to cut, and then moving the eel back and forth (rather than moving the knife).
  • Take a large frying pan and place the eel skin side down. Add 2 tbsp sake and place it on the stove.
  • Place a lid on and steam for 5 minutes over a medium heat. While you wait, preheat the grill or broiler on medium-high.
  • Once 5 minutes are up, remove the pan from the heat and transfer the eel to a wire rack lined with aluminum foil. Place it with the skin side down first and grill for 6 minutes. 
  • Turn over and grill the skin side for 5 minutes.
  • Brush the sauce generously over the skin and grill for 1 minute.
  • Flip and apply the sauce to the meat side. Grill for 1 minute.
  • Repeat the brushing and grilling 3 times on each side.
  • Dish up 2 portions cooked Japanese short-grain rice in a jubako (or similar box) and brush the top with the leftover unagi sauce.
    rice in a lacquerware box brushed with unagi (kabayaki) sauce
  • Arrange the eel on top, drizzle with any leftover sauce and sprinkle with Japanese pepper (sansho).
    grilled eel coated with homemade unagi sauce and shansho pepper over rice in a black lacquerware box
  • Enjoy!
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Keywords grilled eel, unagi, unagi sauce, unaju
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FAQ

What is Unaju?

Unaju (鰻重) is a delicious Japanese dish of grilled eel served with eel sauce and rice in a stacked box called jubako (重箱). It's similar to unadon, except it's served in a box instead of a bowl.

What is doyou no ushi no hi?

During summer in Japan, supermarkets sell eels with the catchphrase "Doyou no Ushi no Hi." This refers to the day of the ox in midsummer and the tradition of consuming foods that start with "U" on this day. It's believed to be good for the body, as it is more susceptible to summer fatigue during this period.

What are the differences between Unaju and Unadon?

Unagi-don and unaju are popular Japanese dishes with grilled eel and unagi sauce atop white rice. The difference lies in their presentation and quantity of eel - unagi-don is served in a bowl, while unaju comes in a lacquer box and tends to be more expensive due to needing more eel to cover the entire rice surface area.

Why is unagi so expensive?

Eels are expensive due to their scarcity. The price of these eels has increased as the number of young fish caught has decreased, and the Japanese eel was listed as an endangered species in June 2014. Unfortunately, it is impossible to completely farm eels as their biology and reproduction remain a mystery. While eels can be raised from fry, they all become male, and the factors determining their sex are unknown.

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