Add the sauce ingredients to a small pot and bring to a boil. Then turn off the heat.
Wash the soybeans and drain. Roast in a frying pan. Once the skins burst open, and they brown and become the hardness of your choice, turn off the heat.
Quickly add to the pot. Let soak just like that for 30 minutes.
After 10 minutes, the beans will have absorbed the liquid and plumped up. Occasionally stir it up.
After 30 minutes, the beans will have absorbed a good amount of liquid and flavor. You can eat them now, but the flavor will blend in even more and they will taste even better if they are eaten the next day.
Story Behind this Recipe
My mother told me about soaking roasted soybeans in soy sauce, but I added some vinegar to suit my tastes more. My whole family loves this flavor. They can be used as a side dish or a snack, so I always have soybeans stocked up.
Don't add the sauce to the frying pan, always add just the soybeans to the sauce pot.