Chop the onions and garlic into small pieces. Cut the beef into bite-sized pieces and season with salt and pepper.
Fry the meat with the onions and garlic in the saucepan. Stir in tomato paste and deglaze with red wine and meat stock. Cut the mushrooms into small pieces, add and let everything simmer for about 1 1/2 hours.
At the end of the cooking time, add the chopped pepper and add the sour cream. Thicken to the desired creaminess with a sauce thickener, add parsley. Season to taste with the spices as needed.