Heat 1 tablespoon of olive oil in a large pan over high heat. Add the sirloin tip roast to the pan and brown it on all sides.
In a small bowl, combine olive oil with Worcestershire sauce, minced garlic, salt, pepper, garlic powder, onion powder, paprika, thyme, oregano and cayenne pepper to use as your seasoning.
Put the roast in the slow cooker and then brush it with the seasoned oil. Arrange the quartered onions around the beef, and pour your beef broth into the slow cooker.
Cover the slow cooker and set it to cook on low for 8 hours. Halfway through cooking, open the lid and arrange chopped russet potatoes and sliced carrots around the roast.
Let the sirloin tip roast rest before slicing thin and serving, making sure to slice against the grain.
