Trim sirloin beef roast, there won’t be a lot of fat to trim,m but remove any large pieces of visible fat.
Remove any twine or elastic netting.
Pat your roast dry with paper towels, and season roast with salt, pepper, garlic powder, and dried rosemary.
Set the instant pot to the “saute” setting, and add oil to the liner.
Heat oil until hot and just smoking.
Brown roast on all sides, about 8-10 minutes.
Once browned, transfer the roast to a plate.
Add the onions and mushrooms to the instant pot liner.
Cook until softened and browned. About 5-7 minutes.
Stir in tomato paste and garlic. Cook for 3 minutes.
Add in the white wine, and simmer until slightly reduced, about 1 minute.
Stir in broth.
Use a wooden spoon, and scrape all the browned bits off the bottom of the liner.
Add roast back into the instant pot liner, place lid on pot.
Lock the lid into place, and set valve to sealing.
Cook on high pressure for 20 minutes.
When cook time is up, let the pressure release naturally for 15 minutes. Temperature of the roast should be about 105 degrees.
After 15 minutes, quick release the remaining pressure. Then carefully remove the lid.
Transfer the roast to a carving board, tent with foil, and let sit for 15 minutes. During this time, the internal temperature should be 120-125 degrees.
Skim the excess fat off the surface of the sauce.
Stir in the marsala. Then bring sauce to a simmer. Let it cook until thickened, about 10 minutes.
Whisk in butter and parsley. Then taste, and season with salt and pepper to taste.
Slice meat thin, to ¼ inch thickness, against the grain, and transfer to a serving dish.
Serve with sauce spooned over the top, and fresh parsley as a garnish.