01 - In a large bowl, combine breadcrumbs and milk and let stand for 5 minutes to hydrate.
02 - Add ground beef, ground pork, finely chopped onion, minced garlic, egg, salt, black pepper, allspice, and nutmeg to the breadcrumb mixture. Mix by hand just until combined—do not overwork.
03 - Divide mixture and roll into walnut-sized balls, about 1 1/4 inches in diameter.
04 - Heat butter and oil in a large skillet over medium heat. Working in batches, fry meatballs until golden brown on all sides, approximately 8 minutes per batch. Remove meatballs and keep warm.
05 - In the same skillet, melt butter. Add flour and whisk, cooking for about 1 minute until lightly golden.
06 - Gradually pour in stock while whisking to avoid lumps. Stir in cream, soy sauce, and Dijon mustard. Season with salt and pepper as needed. Simmer 5 to 7 minutes until sauce thickens.
07 - Return browned meatballs to skillet and coat in sauce. Simmer gently for 5 to 10 minutes until thoroughly heated.
08 - Serve hot, ideally accompanied by mashed potatoes, lingonberry jam, and steamed vegetables.