Sundubu Jjigae (Soft Tofu Stew)

14 oz soft tofu, silken or extra-soft, in one block

4 oz pork belly, thinly sliced

1 tbsp vegetable oil

1 tbsp gochugaru

1 tsp gochujang

3 clove garlic, minced

½ onion, thinly sliced

½ cup zucchini, half-moon slices

4 oz shiitake mushrooms, sliced

2 cup chicken broth

1 tbsp soy sauce

1 tsp fish sauce

1 tsp sesame oil

2 stalk scallion, thinly sliced

1 egg

1 pinch salt