Press the SAUTE button. Add in the butter and let it melt.

Add in the ground beef, red pepper, and red onion and cook, using a spatula to break up the meat.

Press CANCEL.

In a bowl, mix together brown sugar, red wine vinegar, steak seasoning, Worcestershire sauce, and tomato sauce.

Pour sauce on meat in Instant Pot and stir to combine. If you are worried about getting the "burn notice" on your Instant Pot, use a wooden spoon to scrape the bottom of the Instant Pot and loosen up any burned or brown bits on the bottom of the pot (aka deglazing the pot).

Place the lid on the Instant Pot and secure in place. Turn the vent to SEALING. Press the MANUAL button and set the timer for 8 minutes. When cooking is finished, let the pressure NATURALLY RELEASE for 10 minutes and then move the vent to VENTING and release the remaining pressure.

Remove the lid and stir to make sure everything is mixed together, then serve meat on hamburger buns.