Prepare an ice bath. Bring a large pot of water to a boil; add 1 tablespoon salt. Add the grape leaves and gently mix to separate them. Reduce the heat to simmer and cook for 10 minutes. Drain well, plunge into the ice bath and let cool for 2 minutes. Drain well again, separate and lay out on baking sheets lined with paper towels in a single layer. Remove 5 or so of the small or torn leaves and reserve for the bottom of the pan.
Heat 1/4 cup of the oil in a medium high-sided saute pan over high heat. Add the onion, season with salt and pepper and cook, stirring, until the onion is very soft, about 5 minutes; do not allow it to color. Add the rice and cook, stirring constantly, until opaque, about 2 minutes.
Add the stock, currants and 2 tablespoons of the lemon juice; season with salt and pepper. Reduce the heat to medium and cook, uncovered and stirring a few times, until the rice absorbs the liquid, about 7 minutes. (The rice will only be par-cooked; it will continue to cook in the leaves.) Spread the rice out on a baking sheet to cool.
When the rice is cooled, stir in the dill, parsley, green onion, pistachios and lemon zest; taste for seasoning.
Lay a grape leaf on a work surface shiny-side down. Scoop 1 to 1 1/2 tablespoons of the filling (depending on the size of the leaf) in your hand and lightly mold it into a log. Put the rice filling near the stem end of the leaf, fold the stem end over the filling, then fold both sides toward the middle and roll up into a cigar. Continue with the remaining leaves and filling.
Lay the reserved grape leaves on the bottom of a small Dutch oven (this will keep the dolmades from sticking). Tightly fit the dolmades in the pan in a concentric circle, making several layers if needed. Drizzle some of the remaining lemon juice over each layer. Add enough water or stock to just come halfway up the side of the rolls (do not cover them) and drizzle with the remaining olive oil and a pinch of salt.
Cut out a round of parchment to fit over the dolmades. Place a plate on top of the parchment and a bowl on top of the plate (to hold the rolls down while cooking). Bring to a boil over high heat, reduce to a simmer, cover the pot and cook (making sure it is simmering and not boiling), until the rice is cooked through, about 30 minutes. Remove from the heat and let sit, covered, for 10 minutes longer.
Carefully remove the rolls to a serving dish. Serve warm, at room temperature or cold.