Fill a large pot with water and bring to a boil over high heat.

Drain the liquid from the jar of preserved grape leaves and remove them from the jar. Unroll the leaves and drop them into the hot water. Reduce the heat to low and cook for 5-8 minutes, then drain them in a colander and plunge them into a pan of cold water to cool them. 

Gently separate the leaves and spread them on paper towels to drain. If the leaves have stems, clip them off with kitchen scissors. You will need about 50 or 60 leaves for the stuffing. 

Reserve any torn or small unusable leaves for lining the cooking pot. 

Using a Dutch oven, braiser or heavy-bottomed pan, arrange the reserved torn grape leaves plus enough additional leaves to create a layer on the bottom of the pan. This is to keep the stuffed grape leaves from burning during the cooking process. (See Notes) Set the prepared pot aside while you make the filling.

In a large skillet, heat 1/4 cup of the olive oil over moderate heat. Add the onions and, stirring frequently, cook for 4 or 5 minutes until they are soft and transparent. 

Add the rice and stir constantly for 1-2 minutes to coat the rice grains with the oil. Do not let the rice get brown. Pour in the lemon juice, salt, and pepper. Bring to a boil, then reduce the heat to low and simmer for about 8-10 minutes or until all the liquid gets absorbed. The rice will be only partially cooked at this point but will finish cooking during the final cooking.  Do not over cook the rice or it will be mushy after the final cooking.

Remove the skillet from the heat and allow it to cool, then stir in the dill, mint, pine nuts and currants. 

Spread the grape leaf flat, dull side up and place a portion (See Notes) of the filling on the center of the leaf. Turn up the stem end of the leaf, covering the filling. 

Fold over each end to enclose the filling. Beginning again at the stem end, roll it gently but firmly into a compact cylinder. The surface of the leaf will cling together to hold the grape leaf in shape.

Place the stuffed grape leaf, seam side down, in the prepared pot. Continue with the rolling process until all the leaves are filled or the filling is gone. Keep the stuffed grape leaves snug, side-by-side but not squeezed tight as they will expand as they cook. You can add another layer if needed. 

Pour the broth or water into the pot. The water should almost cover the stuffed grape leaves, add more liquid if necessary. Drizzle the remaining 1/4 cup of olive oil over the stuffed grape leaves and squeeze in the juice from the 1/2 lemon. Place an inverted dinner plate over the stuffed grape leaves.  

Set the pot over high heat and bring to a boil. Cover the pot with its lid and immediately reduce the heat to low and simmer for 40-45 minutes. 

Remove the pot from the heat and crack the lid slightly. Allow it to cool down to room temperature. Drain any remaining liquid from the pot, then transfer to a plate, cover with plastic wrap and refrigerate overnight. 

Serve with lemon wedges and yogurt sauce.