Sour Cream and Sumac Sauce
First make the sour cream and sumac sauce by placing all the ingredients in a small bowl. Stir well and set aside or chill until needed.
Preheat the oven to 425 deg F.
In a large bowl, combine all the ingredients for the meatballs except the oil. (It's easiest to mix with your hands)
Using a tablespoon, scoop about a tablespoon and a half of the turkey mixture and shape them into meatballs (ending up with ~ 20 - 22 meatballs)
Pour enough oil into a large frying pan to form a layer about 1/16 inch thick on the pan bottom. Heat over medium heat until hot, then sear the meatballs in batches on all sides. Cook each batch for about 4 minutes, adding oil as needed, until golden brown.
Carefully transfer the seared meatballs to a baking sheet lined with parchment paper and place in the oven for 5 to 7 minutes, or until just cooked through.
Serve warm or at room temperature, with the sauce spooned on top, or on the side.