Set pot to saute and add oil. Rub seasonings on roast on all sides. When hot sear roast on all sides until browned, then turn pot off.
Add broth, Worcestershire sauce and sliced onions into pot. Seal lid and steam valve and set to high pressure for 30 minutes. Do a quick release, open lid and add vegetables.
Add carrots and potatoes. Seal lid and steam valve again and cook on high pressure for 15 minutes with quick release at the end.
If you want to make gravy thicker at the end, remove meat and vegetables. Set pot to saute. In a bowl whisk together some of your broth with 1.5 tbsp cornstarch until smooth. When pot contents bubble, pour this in and stir allowing it to thicken in a few minutes. Serve together immediately.