In a medium bowl, combine the pork, lamb, Pecorino, mint and dill with 1/2 teaspoon of salt and 1/4 teaspoon of pepper. Mix with your hands until combined, then shape the meat into 1-inch balls.
Heat the oil in a large, heavy skillet. Add the meatballs and cook over moderate heat, turning occasionally, until browned and firm, about 15 minutes.
Mix the yogurt and garlic, season with salt and pepper and spoon onto a serving platter. Top with the meatballs and serve immediately.
