Melt the butter and oil together in a large, heavy saucepan. Have a large casserole at hand. Over medium heat brown the meat, several pieces at a time, and as they are browned, remove them to the casserole. Add the onions to the pan and cook until soft over a medium flame.
Add the flour to the beef and toss to cover well, add the browned onions to the beef. Add the wine or stock, and br