1. Finely chop onion.
2. Tricholoma slices.
3. Heat the pan with butter.
4. Add onion and sauté until fragrant, add mushroom slices in your mouth.
5. Fry on medium heat until golden brown, let cool, and put in a blender to make a sauce.
6. In a separate pot, add the butter, boil and add the mushroom sauce.
7. Stir well, add black pepper and salt, and bring to a boil.