Sweet and Sour Meatballs

1 lb ground beef 1/2 cup dry bread crumbs 1/4 cup milk 3/4 tsp. salt 1/2 tsp. Worcestershire sauce 1/4 tsp. pepper 1/4 cup onion, minced 1 egg Mix all together and form balls. Bake on a cookie sheet at 400 degrees for 20 minutes. Sauce: 1/2 cup brown sugar 2 tsp. dry mustard 1/2 tsp. nutmeg 1 cup ketchup Mix sauce ingredients together. Place meatballs in a bag and pour sauce over them and freeze. Thaw, and cook on low for 2-3 hours in a slow cooker. Serve over rice.