Turn the instant pot on Sauté mode. Season steak with salt and pepper. Add 2 tbsp of the oil and wait until it is shimmering hot (about 2 min), then sear the steaks for about 3 minutes per side, or until a golden brown crust forms. Transfer steak to a plate.
Prepare the Sauce
Add another tablespoon of oil to the instant pot and add onions and garlic, cooking until soft,.
Add beef broth to deglaze the pot, scraping up browned bits.
Add steaks to the instant pot and add Worcestershire sauce, and thyme.
Pressure Cook the Steaks
Seal the lid, cook on high pressure for 35 minutes, then allow 10 minutes natural pressure release.
Remove steaks. Set Instant Pot once again to Sauté mode.
Finish the Sauce
Melt butter in the liquid, then add cornstarch slurry (mix cornstarch with water) to thicken the sauce, stirring constantly until it reaches desired consistency.
Adjust seasoning if needed.
Video
Notes
To cook a tougher steak like chuck steak, increase the cooking time to 40 minutes.
For a thicker sauce, adjust the amount of cornstarch slurry.
Let the steak rest for a few minutes before serving for optimum tenderness.
Serve with sides like mashed potatoes or steamed vegetables for a complete meal.