Heat the 1/2 cup oil in a skillet. Add the onion and scallions and saute for about 5 minutes, until soft and transparent. Add the garlic and cook for a few minutes, then add the rice, dill, parsley, lemon juice, salt, pepper, and remaining 1/4 cup olive oil. Stir well, then add the hot water. Cover and simmer about 5 minutes. Remove from the heat and cool. Meanwhile, carefully remove the grapevine leaves from the jar, leaving the brine in the jar. Wash grapevine leaves thoroughly and drain, then with a sharp knife cut the heavy stems from the leaves. (If using fresh grapevine leaves use the same procedure, parboiling leaves for 5 minutes when not tender, then drain.) Line an enameled pan with a few heavy grapevine leaves and set aside. To stuff a grapevine leaf, put it on your working surface rough side up and stem end near you, and place a teaspoonful of the rice mixture near the stem end. Using both hands, fold the part of the leaf near you up and over the filling. Then fold the right side of the leaf over the filling, then the left side, and roll tightly and back away from you and toward the pointed end of leaf. Place the "dolma", seam side down, in the prepared pan. Continue stuffing grapevine leaves until the mixture has been used. (If any grapevine leaves remain, replace in the reserved brine for future use.) Place an inverted plate on the dolmades, then add enough water to cover the dolmades (about 1 to 1-1/2 cups). Bring to a boil, then cover the pan, lower the heat, and simmer as slowly as possible for 1-1/4 hours, then taste one to see if the rice is tender, and continue cooking slowly if necessary. Cool, then chill. Serve cold, as an appetizer or as an entree. Note: An important variation, particularly in Macedonia and Thrace: add a few tablespoons of raisins and pine nuts to the filling when adding the rice. Also, you may vary the size of dolmades as you wish by adding 1-1/2 teaspoons of the filling. However, be consistent to allow them to cook at the same rate. They may be stored in the refrigerator for a week or so.