Place sausage, potatoes, and water into an electric skillett; cover tightly and cook over medium- high heat 8 minutes, stirring occasionally. Meanwhile, cut onion into 12 wedges; core and cut each apple into 8 wedges. Drain sausage and potatoes, and cut potatoes into wedges. In large skillet, cook and stir onion and apples in 1 tablespoon butter 4 minutes, or until apples are just tender. Remove from skillet.