Vegetable broth:
1/2 small onion, cut into big chunks
3 ounces Korean radish, cut into big chunks
3 x 3 inches dried kelp (aka dashima/kombu)
a few mushroom stems
1 tablespoon soup soy sauce
salt and pepper to taste

For the pot:
8 - 10 ounces assorted mushrooms (button, shiitake, oyster, crimini, enoki, etc.)
2 scallions, cut into small pieces
2 ounces watercress
1/2 teaspoon minced garlic
(You can add tofu and/or other vegetables such as Korean radish, napa cabbage, onion, and carrots.)