Place the ground lamb and turkey in a large mixing bowl. Add the shaved onions, panko breadcrumbs, 2 eggs, chopped mint, chopped dill, Italian Seasoning, garlic powder, zest of 3 lemons, 1 1/2 teaspoons salt and 1/2 teaspoon ground pepper. Mix well by hand until the mixture is very smooth.
Place a 14-inch saute pan over medium heat. Add the oil. Once hot, add the meatballs to the skillet. Brown the meatballs for 10 minutes, turning them every minute, to cook evenly.
Meanwhile, whisk 1/3 cup lemon juice, 4 egg yolks, chicken broth, and 1/2 teaspoon salt together. Pour the mixture over the meatballs and simmer another 3-5 minutes to thick the sauce. Shake the pan gently to stir the sauce as it simmers. Serve warm.