For the meatballs:
1 large yellow or white onion, peeled, grated (through a cheese grater)
2 tablespoons butter
2/3 cup milk
4-5 slices of bread, crusts removed, bread cut into pieces
2 eggs
1 pound ground pork
1 1/2 pounds ground beef (80/20)
2 teaspoons salt
1 teaspoon ground nutmeg
1 teaspoon allspice
2 teaspoons black pepper

For the sauce:
6 tablespoons butter
1/3 cup flour
1 quart beef stock
3/4 cup sour cream
Salt
2 to 4 Tbsp of Lingonberry, cranberry, or boysenberry jelly, more or less to taste (optional)