1. In a pan fry onion gently in olive oil until transparent. Add rice and stir over heat for 5 minutes. Addd pine nuts, currants, allspice, dill, and salt and pepper to taste. Cover and cook on gentle heat for 5 minutes. Remove and leave aside.
2. Blanch fresh or preserved vine leaves in boiling water for 3 minutes, adding them in 3 lots. As each lot is blanced, remove to a bowl of cold water, then drain well.
3. Spread a vine leaf on work surface, shiny side down, and place a heaped tsp of the rice filling towards stem end. Roll once, fold in sides and roll into a neat package. Repeat with remaining ingredients.
4. Line base of a heavy pan with 4 vine leaves and pack rolls, folded side down, in closely packed rows. As each row is completed place 3 thin slices of lemon on top before beginning next row.
5. When all rolls are in pan, top with 3 lemon slices and cover with remaining vine leaves. Pour 2 cups water and olive oil over rolls and invert a heavy plate on top to keep rolls in shape during cooking.
6. Bring to a slow simmer, reduce heat, cover pan and simmer gently for 50 minutes. Remove pan from heat and leave until cool.
7. Carefully remove rolls to serving dish, discarding lemon slices. Serve at room temperature, or cover dish and chill before serving. Garnish platter with lemon wedges and serve with a bowl of yoghurt.
Tip : Makes 6 dozen