Warm up ½ cup olive oil in a frying pan and fry the onions until tender. Add the rice and leave it boil in low temperature and covered for 5 minutes. Add the rest of the ingredients apart from the vine leaves. Leave it to boil in low temperature for 5 minutes. Let it cool. Rinse the vine leaves in cold water. If you are using fresh vine leaves put them in boiling water for 3 minutes. Drain the leaves and rinse them with cold water. In the center of each leave (its smooth surface must be on the outside) place a teaspoon of the rice mixture. Fold the leaves covering the mixture and wrap them. Do not wrap them very tight as the rice expands when boiled. Cover the bottom of a sauce pan with vine leaves in order to keep dolmadakia folded. Cover the sauce pan with its lid and leave them boil in low temperature for about an hour. Let them cool down in the sauce pan. Serve with yogurt as starters.