Peel, wash, and chop the vegetables. Add them to a pot with 10 1/2 cups water (2.5 liters) and simmer to make the broth.

Wash the lemongrass. Bruise 4 stalks and finely chop 2 stalks. Heat a pan with a little cooking oil, add some annatto seeds to release their color, then remove the seeds. Add the chopped lemongrass and sauté until fragrant. Add the straw mushrooms and stir-fry, seasoning with a pinch of salt, a little MSG, and soy sauce.

Add the cooked mushrooms to the broth, along with the bruised lemongrass. Season with 2 tablespoons rock sugar (30 g), 1 teaspoon MSG, 1 teaspoon salt, and a splash of soy sauce. Taste and adjust the seasoning as needed. Cut the fried tofu skin into small pieces and add to the pot.