Preheat oven to 350 degrees. Combine beef, sausage, crumbs, onion, bell pepper, milk, egg, salt, seasoning and black pepper in bowl; mix well. Shape misture into 1-inch balls. Place meatballs on two nonstick baking sheets. Bake 25 minutes or until meatballs are browned. Meanwhile, place ketchup, brown sugar, butter vinegar, lemon juice, water, mustard and garlic salt in slow cooker; mix well. Cover; cook on HIGH until hot.
Transfer meatballs to slow cooker; carefully stir to coat with sauce. Reduce heat to LOW. Cover; cook 2 hours
Serves 12