If using vine leaves in brine, first drain them then put them in a large bowl and pour boiling water over them. Make sure the water penetrates well between the layers and let the leaves soak for 20 minutes. Drain. Soak in fresh cold water then drain again and repeat the process once more. This will remove the excess salt.
IF using fresh leaves: Soften them by plunging into boiling water one at a time until limp. Soak and wash the rice in boiling water then rinse under cold tap water. Drain it well.
In a large bowl, mix the rice with the meat, chopped tomato, onion, parsley, celery, salt and pepper. The 2 tbsp of tomato paste will add a Greek flavor.
Place 1 leaf vein side up. Place a heaping tablespoon of filling on the center near the stem edge. Fold the stem up over the filling, then fold both sides toward the middle and roll up like a small cigar. Squeeze lightly in the palm of your hand. This process will become easier after you have rolled a few. Fill the rest. Continue until the filling is used up.
Line the bottom of a large saucepan with a layer of tomato slices or leftover leaves to prevent the stuffing from sticking to the pan and burning. Pack the stuffed leaves in tight layers on the top. Push small pieces of garlic here and there between them. Sprinkle with lemon juice (you can use more than 1 lemon if needed) and add about 1/2 cup water. Some cooks mix a little saffron with the water to give a pale yellow color to the filling this is optional and does not seem to change the taste. The leaves should give a pale lemon color to the rice anyway.
Put a small plate over the rolled leaves to prevent them from coming undone and cover with a lid. Cook over a gentle heat for 2 hours, or until tender, add water gradually as it becomes absorbed.
You may reduce the cooking time to 20 minutes if you use a pressure cooker but the taste is best with long simmering.
Turn onto dish and serve hot.
Lebanese: Cooks will add 4 or more cloves crushed garlic in addition to the slivers and a tbsp dried crushed mint with a little water about 20 minutes before the recipe is done. Others including the Persians, Lebanese and Greeks like 1/2 tsp ground cinnamon added to the filling.