In a large skillet cook sweet potatoes and onion in margarine over medium heat about 10 minutes or until tender, stirring occasionally.
Stir in sausage, apples, sweet-and-sour sauce, and caraway seed. Cook, covered, over medium heat about 3 minutes or until apples are tender and sausage is heated through, stirring occasionally. (If mixture seems thick, add water, 1 tablespoon at a time, to make desired consistency.)
Place spinach on a large serving platter. Top with sweet potato mixture.