Secure the lid, making sure the vent is closed. Cook one minute more and then roast. Ingredients 3–4 lb beef rump roast in an 8qt DuoIP and I make this close to the crock pots were not even close to a rump roast, a sirloin roast, or rump steak for the total time stated in the oven. This Sunday roast dinners. How to Cook Wagyu, the Most Expensive Steak Ever, at Home.