Select “sauté” setting on a programmable pressure multicooker, such as Instant Pot. (Instructions, times, and settings may vary by brand or model.) Select “high” temperature setting; allow to pre-heat. Add oil to cooker. Pat roast dry; sprinkle all sides with salt and pepper. Add roast; cook, turning often, until browned, 10 minutes. Remove from cooker. Add onions and garlic to cooker. Cook, stirring often to scrape browned bits, until just softened, 2 minutes. Press “cancel.” Add browned roast, peppers, broth, butter, and ranch dressing mix.

Cover cooker with lid, and lock in place. Turn steam release handle to “sealing” position. Select “manual/pressure cook” setting. Select “high” pressure for 55 minutes. (It will take 8 to 10 minutes to come up to pressure before cooking starts.)

Let the pressure release naturally. (This will take 10 to 12 minutes.) Remove lid; transfer roast to a deep serving platter. Stir pepper liquid into juices in cooker. Top roast with onion mixture; pour juices in cooker over mixture. Sprinkle with herbs. Serve the meat over mashed potatoes, egg noodles, or rice.