Beef rump roast, which is cut from the primal round in the animal's hindquarter, benefits from long, moist-heat cooking. Slow cooking breaks down the well-exercised protein strands and gristle in beef rump roast. Cooking a rump roast on low heat takes longer, but provides the most tender result, according to Elise Bauer, professional kitchen tester, recipe creator and "Simply Recipes" site owner.
Most slow cookers will hold a 3 to 4 pound of beef rump roast, according to slow cooker manufacturer and distributor, Jarden Corporation. The USDA Food Safety and Inspection Service recommends cooking a 2 to 4 pound of beef rump roast until it reaches an internal temperature of 145 Fahrenheit. Cooking a 3 pound beef rump roast on the "Low" setting, as Betty Crocker.com advises, takes 9 hours. Switch your slow cooker to "High" and you reduce that cooking time to just 5 hours, according to the Jarden Corporation.
Searing the Meat
Oils such as olive, almond, sesame or walnut oil create a barrier on the surface of the roast, adding layers of flavor. Searing the meat just before putting it in the slow cooker produces a richer color and crust than the slow cooker alone can provide, and helps to break down any fats in a well-marbled roast. To sear the meat before adding it to the slow cooker, set a skillet on high heat. Add 1 tablespoon of oil, and allow it to heat for about 5 minutes. Add the roast, turning once on each side to caramelize the natural sugars in the meat, and evenly brown the surface layer.
Braising the meat -- essentially immersing it in liquid and cooking it over a period of time -- is the secret to tenderizing tougher cuts of meat according to Anne Gardiner and Sue Wilson, authors of "The Inquisitive Cook." Collagen softens in hot liquid, allowing tough muscle fibers to unfold which produces a moist and tender result. While you can use plain water to braise your rump roast, the result will be less flavorful than if you used wine, spirits or juice instead. Acidic liquids such as red wine, spirits or juice help break down fats and penetrate the meat with flavor. Use only wine and spirits that you would drink on their own and avoid using cooking sherry, which contains nitrates and added salts.
Most pot roast recipes include a variety of vegetables such as carrots, onions, potatoes and celery, along with tomatoes and spices. Layer any vegetables on the bottom of the slow cooker so that the juices from the roast drip onto them. Most slow cookers will hold up to 5 cups of vegetables along with a 3 to 4 pound roast. If your roast is too large, cut it in half and use only what you need for that meal.