In a large bowl, mix the ground meat, rice, four ounces of the tomato sauce, the butter, salt and pepper together with your hands. Set aside. Rinse the grape leaves in cool water and cut off the stems.
Lay a grape leaf on a plate, vein side up. Take 1 tablespoon of the meat mixture and roll it into a sausage shape. Center it across the bottom half of the grape leaf, leaving a one-half-inch border on each side. Fold the bottom of the grape leaf over the stuffing, roll a snug revolution, and turn in the sides of the leaf and continue rolling it into a neat package. (The rolled grape leaf should look like a small cigar.) Place it in a heavy, non-stick pot, seam side down. Continue with the remaining meat mixture and grape leaves.
When the bottom of the pot is covered with the rolled grape leaves, drop in a teaspoon of the sliced garlic. Continue layering the rolled grape leaves and garlic until you have used up all the grape leaves and meat.
Add water to cover, pour in the remaining 4 oz. of tomato sauce. Place a small, fireproof plate on top of the leaves to prevent them from floating up. Bring the water to a boil, then reduce the heat to low and simmer the grape leaves uncovered for 40 minutes. You may need to add a little water at the end if the pot dries out before the time is up. During the last five minutes add the lemon juice.
Serve the grape leaves warm with lebna or hummus.
Makes 80 to 90 rolls