Roast the soy beans in a frying pan until golden brown (it'll become aromatic and the skins will crack in about 4-5 minutes).
Turn off the heat and let rest for a little while. Then, swirl the soy sauce and shake the pan so that the beans are dried in the residual heat. Once they have fully absorbed the soy sauce, they're done.
When I poured on a roughly equal amount of soy sauce and mentsuyu sauce, it formed a crispy layer on the surfaces and was delicious (it sticks to the beans while hot, but becomes crispy and flaky once cooled).
Story Behind this Recipe
I thought up this snack as a way to encourage my kids to chew their food thoroughly. This dish is also great as an appetizer with drinks.
If using the pre-roasted soy beans that are sold for Setsubun (Japanese festival to celebrate the first day of spring), adjust the cooking time accordingly.