In A Nonstick Skillet, Cook Turkey And Onion Over Medium Heat Until Meat Is No Longer Pink; Drain. Add The Tomatoes, Macaroni, Green Pepper, Tomato Sauce, Water And Chili Powder. Bring To A Boil. Reduce Heat; Cover And Simmer For 20 Minutes Or Until Macaroni Is Tender. Garnish Servings With Sour Cream.