Vietnamese Style Vegetarian Curry Soup

2 tablespoons vegetable oil

1 onion, coarsely chopped

2 shallots, thinly sliced

2 cloves garlic, chopped

2 inch piece fresh ginger root, thinly sliced

1 stalk lemon grass, cut into 2 inch pieces

4 tablespoons curry powder

1 green bell pepper, coarsely chopped

2 carrots, peeled and diagonally sliced

8 mushrooms, sliced

1 pound fried tofu, cut into bite-size pieces

4 cups vegetable broth

4 cups water

2 tablespoons vegetarian fish sauce (Optional)

2 teaspoons red pepper flakes

1 bay leaf

2 makrut lime leaves

8 small potatoes, quartered

1 (14 ounce) can coconut milk

2 cups fresh bean sprouts, for garnish

8 sprigs fresh chopped cilantro, for garnish