our everyday life

How to Cook a Boneless Top Sirloin Roast in a Slow Cooker

by Meg Jernigan

Boneless top sirloin roast is one of the leaner cuts of beef, and is typically broiled, grilled or roasted. The low heat in a slow cooker mimics the low to medium temperature of a slow oven, and the long cooking time assures a tender outcome. Slow cooking can leach some of the flavors out of the beef, however, leaving you with a stringy, tasteless roast, so bring on the flavor with bold seasonings. Use vegetables that can stand up to long cooking times for a true one-dish meal.

Peel and cut up potatoes, onions and carrots or other root vegetables such as parsnips or turnips. Arrange the cut-up vegetables in the bottom of the slow cooker.

Dissolve beef bouillon cubes in warm water and pour the liquid over the vegetables, or pour in just enough fresh beef stock to cover the vegetables.

Sear the sirloin roast over high heat in a heavy pan. Add a little peanut, vegetable or canola oil, heat the pan until the oil shimmers and carefully lay the roast in the pan. Let it cook for a couple of minutes, then turn it. Immediately after turning it, season the cooked side with salt and pepper, a commercial seasoning blend or your own section of herbs and spices. Sear and season the other side.

Place the seared roast on top of the vegetables in the slow cooker and put the lid on. Cook for around 6 hours on high, or around 8 hours on low.

Take the roast out of the slow cooker, cover it loosely and let it rest for about 15 minutes. While the meat rests, use a slotted spoon to remove the vegetables. Transfer the cooking liquid to a saucepan and bring it to a slow boil. Mix a tablespoon or two of flour into a cup of cold water and whisk the flour and water mixture into the boiling liquid. Stir and cook until the gravy is as thick as you like it.

Slice the meat and serve the vegetables and gravy on the side.

Items you will need
  • Root vegetables
  • Beef bouillon or beef stock
  • Heavy pan
  • Oil
  • Salt and pepper
  • Slotted spoon
  • Saucepan
  • Flour
  • Whisk


  • Before you sear the sirloin roast, cut slits in the meat every few inches with a sharp knife. Peel and thinly slice a clove of garlic, and press a slice into each slit. Alternatively, fill each slit with fresh herbs.
  • If you’re pressed for time, don’t sear the meat. Searing adds color and flavor, but isn’t absolutely necessary.
  • Coat the meat lightly with a little flour before searing it. The liquid in the slow cooker may thicken sufficiently from the flour, making it unnecessary to make gravy after the meat is cooked.


  • Test the meat’s temperature with a probe thermometer. The USDA recommends cooking beef roasts to an internal temperature of 145 degrees Fahrenheit for medium-rare, 160 degrees Fahrenheit for medium and 170 degrees Fahrenheit for well-done.
  • Make sure the roast is fully thawed before you put it in the slow cooker. If the meat is frozen, the interior won’t cook at the same rate as the exterior.
  • Don’t lift the lid to peek at the roast -- opening the slow cooker will drop the temperature and add cooking time.
  • Don’t overfill the slow cooker. It shouldn’t be more than 2/3 full.

About the Author

Meg Jernigan has been writing for more than 30 years. She specializes in travel, cooking and interior decorating. Her offline credits include copy editing full-length books and creating marketing copy for nonprofit organizations. Jernigan attended George Washington University, majoring in speech and drama.

Photo Credits

  • Jupiterimages/Comstock/Getty Images