Prepare the Roast
Preheat your oven to 325°F (165°C). Pat the rump roast dry with paper towels, then season generously with salt, pepper, garlic powder, onion powder, thyme, and rosemary on all sides.
Sear the Roast
In a large skillet or Dutch oven, heat the olive oil over medium-high heat. Sear the roast on all sides until it’s browned, about 3-4 minutes per side. This step helps lock in the flavors.
Transfer to Roasting Pan
Place the seared roast in a roasting pan or slow cooker. Add the onion, garlic cloves, carrots, and potatoes (if using) around the roast.
Add Broth and Seasonings
Pour the beef broth, Worcestershire sauce, and tomato paste (if using) into the pan, around the roast. The liquid should come about halfway up the side of the roast. Cover the pan tightly with a lid or aluminum foil.
Roast or Slow Cook
Oven Method: Roast for about 3–4 hours in the preheated oven, or until the meat is tender and easily shreds with a fork.
Slow Cooker Method: Cook on low for 6–8 hours or on high for 3–4 hours until the roast is tender.
Rest and Slice
Remove the roast from the pan and let it rest for 10-15 minutes. Slice the roast thinly against the grain for the most tender pieces.
Serve with Pan Juices
Serve the rump roast with the cooked vegetables and a drizzle of the pan juices for extra flavor. For a thicker gravy, you can simmer the pan juices on the stovetop with a slurry of cornstarch and water.