For the Meatballs:

• 1 pound ground pork
• 1 pound lean ground beef
• 1/2 cup breadcrumbs (Panko recommended)
• 1 medium onion, finely chopped or shredded
• 2 large egg yolks
• 1/2 teaspoon salt, or to taste
• 1/2 teaspoon black pepper, or to taste
• 1/4 teaspoon ground nutmeg
• 1/4 teaspoon ground allspice
• 1/3 cup milk
• 2 tablespoons olive oil, for frying

For the Gravy:

• 6 tablespoons unsalted butter
• 1/3 cup all-purpose flour
• 3 cups low-sodium beef broth
• 1/4 teaspoon salt, or to taste
• 1/4 teaspoon black pepper, or to taste
• 3/4 cup sour cream

For Garnish:

• 1 tablespoon fresh dill, chopped
• 1 tablespoon fresh parsley, chopped