Combine meat, onions, bulgur, 1/2 of tomato sauce, lemon juice, parsley, mint, and seasonings. Blend well. Cut stem from washed grape leaves. Place rough side up and place a small amount of the mixture on the leaf, tuck in the sides and roll up. Cover bottom of pan with several plain leaves; then arrange stuffed leaves side by side in layer. Pour remainder of tomato sauce over top, cut butter into pieces and place on top, scattering here and there. Add 1 cup of water, cover and cook for 45 minutes. Serve hot. Try a toping of yogurt (optional). Variation: Use cabbage leaves in place of grape leaves. Soften leaves in boiling water until limp; follow as above.