Cleaned meat is cut into 4 steaks, which are crushed on both sides with a wooden mallet. Spread with vegetable oil and scatter pepper. Make a marinade of beer, mustard, 1 tbsp vegetable oil, chopped parsley, salt and pepper, which put the steaks and leave to stand for 24 hours. Steaks drain and fry, so to remain juicy inside. Onions cut into slices and fry until lightly redness, add salt and spread over the steaks. From marinade 1 tsp flour and a little broth (water or cream) is made sauce, which is served separately.