Bring water to a boil and add the Tom Yum herbs.

Add the straw mushrooms and cook for a bit. Then add the canned fish along with the tomato sauce. Let it come to a boil again, then turn off the heat.

Season to taste with crushed chilies, lime juice, fish sauce, and a little sugar. Ladle the Tom Yum soup into bowls, garnish with green onions and cilantro, and serve.