Clean, wash and cut the cabbage into pieces. Steam in little salt water for about 12 minutes. Pour the cabbage on a sieve and let it drain. In the meantime, grate the mushrooms, possibly halve them.
Peel and finely chop the onion. Cut the Kasseler into small pieces. Heat oil in a pot. Brown the mushrooms, onion and meat in it and take it out. Melt the fat in the frying fat. Add flour and sweat briefly.
Deglaze with broth and milk. Bring everything to the boil while stirring and simmer at low heat for about 5 minutes. Grate cheese and stir into the sauce. Add prepared ingredients and heat up again. Season to taste with salt and pepper.
Place the vegetable ragout in a bowl and serve. Boiled potatoes taste good with it.