Moisten steak with water on both sides; sprinkle with meat tenderizer. Poke meat all over with fork. Set aside. Combine cumin with dry mustard, sugar, chili powder and 2 tablespoons beer. Spread on 1 side of steak. Saute onion and garlic in oil until golden. Add mushrooms and tomatoes. Saute 5 more minutes. Add stuffing mix, salt and pepper; toss lightly.
Spread over steak and roll up jelly roll style starting at small end. Tie 4 or 5 times with butcher string. Place on rack in baking pan. Cover with remaining beer and water. Bake for 2 hours at 300 degrees, basting frequently. Remove string before carving. Serves 6.
