the grape leaves have already been blanched, simply rinse and set in a colander to drain. If they are fresh, wash well and soak in hot salted water for 5 minutes, then drain.
Heat 1/2 cup of olive oil over medium heat, and sauté the onion until soft.
Add rice, half the lemon juice, herbs, salt, pepper, and 1/2 cup of water, increase heat and bring to a boil. Boil for 2 minutes and turn off heat.
Allow the filling to sit for 5-10 minutes.
Place one teaspoon of filling at the stem end of a grape leaf and roll. Continue until filling has been used. (If any of the leaves are very small, use two for each roll.)
Line the bottom of a pot with unused or broken grape leaves and place the rolls, seam side down, in the pot in layers. Add 1/3 cup of olive oil and the 3-4 cups of water (enough to reach the top of the rolls). Place a plate on top of the rolls to hold them securely while cooking and bring to a full boil. Cook for 20 minutes or until only the sauce remains.