Soak the rice in cool water to cover for about 30 minutes. Drain.
While the rice is soaking, melt the butter in a medium sauté pan or skillet over low heat. Add the onions and cook, stirring occasionally, until translucent and tender, about 10 minutes. Add the garlic and spices and cook a few minutes more. Let cool about 10 minutes. Combine the onion mixture, rice, ground lamb, pine nuts, currants, parsley, and salt in a bowl.
Snip the stems off the grape leaves and place smooth side down on a table. With your hands shape about
Arrange seam side down and close together in a single layer in 2 pans. Pour half the olive oil and lemon juice over the dolmas in each pan, then add hot water to just cover. Weight with plates to keep them from unrolling.
Heat the liquid to boiling and cover the pans. Reduce the heat and simmer about 30 minutes. Uncover the dolmas so that they can cool quickly. As soon as they can be handled, remove the dolmas with a spatula and arrange on platters (see Note). Serve warm with lemon wedges and yogurt.