Question: how long to cook a 2 1/2 pound roast to medium rare?
Answer: Roast for about 13-15 minutes per pound for rare, 17-19 minutes for medium, and 22-25 for cooked through. Check the meat with a thermometer to make sure it is the temperature you want it--145°F for medium rare, 160°F for medium. (Baste the roast a couple times while cooking, and keep an eye on the vegetables.