1. Wash the lamb and pat the pieces dry. In a wide pan or pot, add the olive oil and butter and brown the meat on all sides. Remove the meat and add the spring onions to the pot. Sauté them, then return the meat to the pot. Add 1 liter of water to cover the meat and boil over medium heat for about 1 hour.
2. In another pot, cut the cleaned lettuce, which we have chopped into large pieces, and blanch them briefly to remove any bitterness. Once the meat is ready, add the lettuce and dill, and a little water if needed. Boil for 15 minutes. For the avgolemono (egg-lemon sauce): Beat the 2 eggs with the lemon juice and the cornstarch mixed with a little water.
3. Add spoonfuls of the hot broth to the egg mixture to bring it to the same temperature as the food, then pour it into the pot.
