Remove and discard the heads of 10 g dried sardines (niboshi).
Pour 1000 ml water into a pot and add the dried sardines and 10 g dried kelp (kombu). Cover and soak for 30 minutes. (If making it plant-based, add 1-2 dried shiitake mushrooms instead of niboshi.)
After 30 minutes, place the pot on the stove and start heating on medium-low.
Add 15 g bonito flakes (katsuobushi).
Allow the dashi to heat up slowly until small bubbles start to appear, then turn off the heat. Do not let it boil.
Take a large heatproof bowl and place a sieve lined with kitchen paper.
Pour the dashi through the sieve, allowing the clear broth to pass through into the bowl.
The dashi is complete and ready to use. Leftovers can be stored (see note).
Udon and Broth
Boil 5 portions udon noodles according to the instructions on the packaging. Once cooked, pour through a sieve of colander to drain and wash with fresh hot water to remove any excess starch.
Pour the dashi broth back into the pan and add 5 tbsp Japanese soy sauce (koikuchi shoyu), 2 tbsp mirin and bring to a boil over a medium-high heat.
Let it bubble for 1-2 minutes to burn the alcohol away from the mirin, then turn off the heat and mix in ½ tsp salt.
Divide the noodles and broth into serving bowls and add the toppings of your choice.
Enjoy!
Notes
Leftover dashi or broth can be stored for 5 days in the fridge or up to 1 month in the freezer. If freezing, divide into portions for convenience.If you don't want to make your own dashi from scratch, see in post for alternatives.See post for more topping ideas.NOTE: The nutritional value is based on drinking up the soup (we usually don't drink all the soup when it comes to udon.)