Vegan Jjajangmyeon (Noodles in Black Bean Sauce) - The Foodie Takes Flight

Name: Vegan Jjajangmyeon (Noodles in Black Bean Sauce) - The Foodie Takes Flight
Cuisine: Asian, Korean
Ingredients: 5 dried shiitake mushrooms for mushroom broth; 2 cups boiling hot water for mushroom broth OR; 6 fresh shiitake mushrooms (add to the 80g mushrooms below), see notes; 2 cups vegetable broth; 6 servings dry wheat noodles , dried jjajang noodles, or dried udon noodles (each dry serving is around 65g) see notes; 2 tbsp corn starch; 1/4 cup room temperature water; 3 tbsp neutral oil; 5 cloves garlic minced; 1 large onion diced; 1 tsp minced ginger; 4 green onions thinly sliced makes around 1/2 cup sliced; 1/2 cup black bean paste or chunjang around 190g; 200 g zucchini diced (from 1 large); 250 g potato peeled and diced (from 2 small); 80 g fresh shiitake mushrooms diced (around 7 pieces), see notes; 250 g cabbage chopped into small squares (from 1/2 small head); 3 tbsp cane sugar; 2 1/2 tbsp vegetarian mushroom oyster sauce or soy sauce, to taste; Ground pepper to taste; More vegetable broth or water, if needed; 1 tbsp toasted sesame oil optional; Slurry