Put on a saucepan with water. Meanwhile, cut the cabbage into fine strips and cook for about 10 minutes.
Peel the onions and cut into fine cubes. Then clean the mushrooms with a brush and dice them as well. You should avoid washing the mushrooms, otherwise they will soak up water like a sponge.
As soon as the cabbage is cooked, drain the water, mix with the mushrooms and the onion and fry well in a pan with hot oil. I fry the vegetables until the onions are golden yellow. Season with salt and a lot of pepper.