Vegan Kimchi Soup

Name: Vegan Kimchi Soup
Ingredients: 14-ounce tub extra-firm tofu (see Note); 1 tablespoon toasted sesame oil or neutral vegetable oil; 1 medium onion, finely chopped; 3 to 4 cloves garlic, minced; 4 cups green cabbage, preferably napa, sliced (swap in savoy or green cabbage if need be); 6 to 8 ounces mushrooms, any variety, stemmed and sliced; 2 teaspoons grated fresh or bottled ginger, or more, to taste; 1 teaspoon gochugaru, or more, to taste; 6 cups water, plus more as needed; 2 vegetable bouillon cubes; 2 tablespoons soy sauce; 14.5-ounce can diced tomatoes (fire-roasted, if available); 4 stalks bok choy or 1 medium baby bok choy, sliced; 1 tablespoon gochujang paste, more or less to taste; 1 cup kimchi, mild or medium, or more if desired; 2 scallions, thinly sliced plus more (green parts) for topping; 1/3 cup fresh cilantro leaves, plus more for topping; Cooked rice (about 1 1/2 cups); Bean-thread noodles (about 4 ounces), cooked and cut into shorter lengths; 1 medium sweet potato, peeled, diced and cooked