Sprinkle carp filets with lemon juice and season with salt and pepper. Cover both sides with flour an fry fish filets on both sides. Remove and keep warm.
Cut mushrooms into slices and fry them with onion in the same pan. Fold in tomato paste. Mix well sour cream and 1 tbsp. flour and thicken the sauce. Add wine, and season with salt and pepper and simmer some minutes. Add fish filets and let all simmer about 10 minutes more.
Serve and sprinkle with chopped parsley.