These spice-loaded meatballs have a Turkish inflection. The warm yogurt sauce adds tang and richness, along with a sprinkling of tart sumac powder and chopped mint. American "Greek-style" yogurt is not always tart enough, but it can be thinned with a bit of buttermilk or even lemon juice. Whisking it with cornstarch and egg produces a silky sauce. Though the ingredient list looks long, this is a simple and impressive dish to make.
Serve with rice, orzo, pita bread or potatoes.