Preparation

• In a large bowl, combine the beef, rice, onion, tomato, 3 Tbs. of the oil, the tomato paste, 2-1/2 tsp. kosher salt, and 1/2 tsp. pepper. Refrigerate, covered, until ready to use.
• Add 6 cups of water to a medium Dutch oven or other heavy-duty pot. Bring the water to a boil over high heat, then reduce the heat to low. Gently unfold and loosen the grape-leaf bunches (don’t worry if you can’t unfold each bunch completely), add to the water, and simmer until they soften, 10 to 12 minutes.
• Drain the grape leaves, and carefully run under cold water to cool. Transfer the damp leaves to a plate, then cover lightly with a damp kitchen towel to keep moist, reserving any torn leaves. Working with one leaf at a time, slice away any remaining hard stem.
• Put a grape leaf on a work surface smooth side down. Depending on the size of the leaf, the amount of filling can vary from 1 tsp. to 1 Tbs. Put the filling at the stem end of the grape leaf, and roll up from the stem to enclose; it should be plump but not overstuffed. Fold the two sides of the leaf over the filling, and continue rolling from the stem end. Transfer to a baking sheet seam side down, and repeat until you have used all the filling and/or whole grape leaves.
• Line the bottom of a large Dutch oven or other heavy-duty pot with a circle of parchment. Arrange a bed of the reserved torn leaves to cover the parchment (don’t worry if you don’t have enough leaves). Put the dolmades on top of the torn leaves in a circle, placing them as close together as possible and stacking them in two layers, if necessary.
• Gently pour 1 cup of hot water, the remaining 2 Tbs. oil, and the lemon juice over the dolmades. Cover with another circle of parchment, then cover with a heavy plate to prevent the dolmades from floating while cooking.
• Cover the pot with the lid ajar, and cook over low heat until the rice is cooked through, 45 to 50 minutes.
• Gently remove the dolmades from the pot, and drain on paper towels. Transfer to a platter, and sprinkle with flaky sea salt. Serve warm or at room temperature with the lemon wedges.