Brown ground beef and 1/2 cup onion in a skillet, drain excess fat. Stir in taco seasoning, water and tomato sauce. Bring to a boil and simmer 1 min. Spread meat mixture into a greased 9 x 13 inch baking pan. Top with green chilies, beans, and potatoes.
In mixing bowl, combine soup, milk, 1/4 cup onions, green pepper, sugar and Worcestershire sauce and pour over potatoes. Sprinkle with paprika. Cover with foil and bake at 350 for 1 hour.
Remove foil and bake another 15 minutes, or until lightly browned. Allow to stand 10 minutes before serving.