1. Heat 1 tablespoon of olive oil in a frying pan add the onions and saut until soft and transparent.
2. Add the rice, mix well then cover and cook over a low heat for 5 minutes shaking the pan from time to time to prevent it sticking .
3. Add the remaining filling ingredients, stir to mix and continue to simmer for a further 5 minutes. Remove from the heat and allow to cool.
4. Meanwhile, if using tinned vine leaves rinse well in cold water. If using fresh vine leaves, blanche in boiling water for 3 minutes. Drain and rinse in cold water.
5. Place the vine leaves, shiny side down-wards on a clean surface or plate. Put a heaped teaspoon of the filling in the centre of each leaf, fold the sides of the leaf over the filling then roll it up. Do not roll them up too tightly as the rice swells during cooking.
6. Place the vine leaf parcels in the bottom of a large saucepan seam side down. Sprinkle with the lemon juice, olive oil and enough boiling water to cover by 5cm/2inches. Place a plate over the parcels to prevent them from springing open, then cover the pan with a lid and simmer over a low heat for about 1 hour, adding more boiling water if necessary to prevent them burning.
7. Allow to cool in the cooking water, drain well and serve cold.