01 - In a large bowl, combine breadcrumbs and milk. Allow to soak for 5 minutes until softened.
02 - Add ground beef, ground pork, onion, garlic, egg, salt, black pepper, allspice, and nutmeg to the bowl. Mix gently until just combined to preserve tenderness.
03 - Roll mixture into walnut-sized balls, roughly 1 1/4 inches in diameter, arranging them on a tray.
04 - Heat butter and vegetable oil in a large skillet over medium heat. Cook meatballs in batches for about 8 minutes, turning to achieve even browning. Transfer to a plate and set aside.
05 - Melt butter in the skillet. Whisk in flour and cook for 1 minute to form a roux.
06 - Gradually pour in the stock, whisking constantly to avoid lumps. Stir in heavy cream, soy sauce, and Dijon mustard. Simmer, stirring, until thickened, 5 to 7 minutes.
07 - Return meatballs to the skillet, turning to coat in sauce. Simmer gently for 5 to 10 minutes until meatballs are fully heated through.
08 - Plate meatballs topped with sauce. For a traditional touch, accompany with mashed potatoes, lingonberry jam, and steamed vegetables.