1In a bowl, combine the uncooked beef, beans, chili powder, oregano. Spoon into uncooked manicotti shells; arrange in a greased 13 in by 9 in by 2 in baking dish. Combine water and picante sauce; pour over shells. Cover and refrigerate overnight.
2Remove from the refrigerator 30 minutes before baking. Cover and bake at 350 degrees for 1 hour. Uncover and spoon sour cream over the top. Sprinkle with the cheese, onions and olives, if desired.
Bake 5 - 10 minutes longer or until the cheese is melted.