Heat the pan on medium and add 100 g ground pork. Sprinkle it with 1 pinch salt and pepper and fry until browned. (You can add a little oil if it's sticking, but if you're using a non-stick pan, generally the pork has enough fat to prevent it from sticking to the pan.)
Add the ½ onion (finely diced) to the pan and fry with the pork until slightly softened.
Next, add ½ tsp sake, ½ tsp Japanese soy sauce (koikuchi shoyu) and ½ tbsp yellow miso paste (awase) and mix until evenly distributed through the pork.
Push the pork to one side of the pan and on the empty side, add 1 tbsp toasted sesame oil, ½ tbsp chili bean sauce (toban djan) and 1 tsp grated garlic. Mix them together for about 30 seconds - 1 minute. Once fragrant, mix with the pork.
Pour 200 ml chicken bouillon into the pan, add 300 g firm tofu (cubed) and bring the mixture to a boil, mixing occasionally. Once bubbling, turn the heat down to a simmer.
Add 1 tbsp sake, ½ tsp Japanese soy sauce (koikuchi shoyu), ½ tbsp oyster sauce and ¼ tsp ground black pepper to flavor the sauce.
Simmer until the sauce is reduced to about half, mixing occasionally.
Take a small bowl and mix 2 tbsp cold water with 2 tsp cornstarch. Once smooth, add it to the pan and mix.
Once the sauce has become thick and glossy, add 2 tsp chili oil (rayu), mix and turn off the heat.
Sprinkle with chopped finely chopped green onions and chili threads (optional).
Enjoy!
Notes
For vegetarians: Replace pork with a meat alternative and use vegetarian miso paste, mushroom sauce instead of oyster sauce, and vegetable bouillon.
Miso options: Yellow (awase) miso paste works best, but you can use red or white miso, or mix red and white in equal parts to create your own awase miso.
I recommend using an Asian-style chicken bouillon to make the stock. But you can also use other types of bouillon if that's easier for you.
To adjust spiciness: First, remove the chili oil topping for milder flavor, then substitute yellow miso for chili bean paste for an even milder version.
Store leftovers in the refrigerator for up to 3 days. Reheat refrigerated Mabo Dofu in a microwave or pan before serving.