If you are a fan of sweet and sour meatballs or little hot dogs in a flavorful sauce, you will love this sweet and spicy kielbasa recipeit is just as delicious and even quicker to make. It is a simple dish made with just four ingredients; finely chopped onion, brown sugar, and mustard flavor this easy slow cooker sausage dish which can be served as an appetizer or even as a dinner entree with a green vegetable, potatoes, macaroni salad, or baked macaroni and cheese on the side. As an appetizer, you can serve it right from the slow cooker, and the recipe is easily scaled up for a large party. Perfect for the big game or even a cookoutall you need are some toothpicks and plenty of napkins.