This is a fool-proof recipe for medium-rare beef. It has never failed me. Adjust time accordingly if you want it rare or well done, but only by a minute or two. If the roast size in not an even number (say 4 1/2 lbs) roast for the lesser amount of time if you like it med-rare. Another minute or two for the 1/2 pound is not suggested. Roast time is for a 4 lb roast.