1 (about 1/2 cup) small onion, coarsely chopped in a food processor
1/2 cup sour cream
1 large egg, lightly beaten
3 tablespoons fine dry breadcrumbs
1 1/2 teaspoons coarse salt
Freshly ground pepper
1/2 teaspoon ground allspice
1/4 teaspoon ground nutmeg
1 tablespoon vegetable oil
2 tablespoons dry red wine
2 tablespoons all-purpose flour
2 cups homemade or low-sodium store-bought beef stock
1/4 cup coarsely chopped fresh flat-leaf parsley
Preheat oven to 275 degrees. Combine beef, pork, onion, sour cream, egg, breadcrumbs, salt, pepper, and spices with hands. Shape into 1 3/4-inch balls. Freeze on a rimmed baking sheet 30 minutes. Reroll in hands.
Heat oil in a 12-inch nonstick skillet over medium-high heat. Cook meatballs, shaking skillet, until browned and cooked through, about 6 minutes. Keep warm in oven on a clean rimmed baking sheet.
Pour off fat and large brown bits from skillet. Add wine; cook over medium heat, stirring, until mostly reduced. Whisk in flour; add stock. Raise heat to medium-high. Simmer, stirring, until thick, 8 to 10 minutes. Pour through a sieve. Top meatballs with sauce and parsley