This dish and what it takes to make it "just right" reminds me of Juk Gae Jang. Everyone seems to have their own recipe and 'secret ingredients' handed down from their grandmother.
I've had many versions of tofu stew to include combinations of stew, tofu, pork, and beef. I've had mild to very hot flavors and prefer the hot and spicy recipes.
This hot stew dish is immensely popular among Koreans and recipes listed have to be the most comprehensive varieties - they have it all! What makes a good Soon dubu jjigae, based on what I ate in Korea, is the hot and spicy flavor with a perfect balance between ingredients such as anchovy, sesame seed oil, hot pepper flakes, and seafood.
With the mild tofu being bland, the right blend of ingredients lends a great touch and consistency to every bite to include the tofu. Unlike the two other recipes offered here, this one calls for tuna!