Press the "saute" function on your instant pot and let it heat up for a few minutes before adding any oil
While it is heating, prepare your roast
Pat your 3 lb (+- ½ lb) roast dry with paper towel then season generously with salt and pepper on all sides (alternatively season one side, then the other once it's in the IP).
Add the olive oil to the instant pot then place the roast seasoned size down and let it brown for 4 minutes. If you. haven't already, then season the rest of the roast. After 4 minutes, rotate the roast and brown the bottom for 3½ minutes, then each side for 2½ minutes respectively.
Once the roast has been seared on all sides, remove it to a plate and set it aside.
Add the sliced onions to the IP (adding more olive oil only if necessary), and saute them for 2-3 minutes until translucent, then add the minced garlic for only 30 seconds so it doesn't burn but is fragrant.
Deglaze the IP with the 1 cup of stock, making sure to scrape off the fond (brown bits on the bottom of the pot) with a wooden spoon.
Add the worcestershire and bay leaves and rosemary and mix well, then place the rack back into the IP and return the roast to the pot.
Depending on the thickness of your roast cook on High Pressure for 3 minutes then 30 minutes natural release for a 2.5" thick roast OR for a thicker 3.5" roast cook on High Pressure for 3 minutes and let it natural release for 35 minutes. (if you have an even thicker roast add 5 min per inch for natural release)
Once the natural release has finished, remove the lid and insert a meat thermometer to check the temp. If you like a med rare roast then cook until internal temperature of 120° F is reached. If it is not there yet, return the lid to the pot and let it sit on the "keep warm-natural release" function for longer. The temp of the roast should go up by 7°-10° every 5 minutes, so if it's off by 10 degrees F give it 5 more min, 20 degrees F then 10 minutes etc.
The thicker your roast is, the longer it will take to get to that temp, so if you're starting off with a roast that is thicker than what I have (3.5") add 5 +_ minutes to the initial natural release and go from there.
Once your roast has reached the desired 120° F, remove it to a sheet pan and cover it with tin foil and allow it to rest for 30 minutes to an hour before slicing thin. I like to use this roast for beef dip, so I give it an hour to rest, then slice it on my meat slicer nice and thin. If you don't have a meat slicer, you can still slice it thin, but the longer it has had to rest (or even chill in the fridge), the easier it will be to slice.
If you want to make beef dip sandwiches, or thin roast and want an au jus or gravy, you can use the pan drippings to make either.
For Au jus. Taste the drippings for flavor and add seasoning if needed. Salt, pepper, or more worchestershire. You can strain out the onions etc if you like a typical au jus, or leave them in.
If you want a thicker, typical gravy, then set the IP back to saute function, and taste again for seasoning (add what you need). Combine 2 Tbsp all purpose flour with 4 Tbsp water, and stir to remove lumps then add this to your IP a little at a time, until the desired consistency is achieved. Taste for seasoning and adjust if necessary. Serve over mashed potatoes, or with fries for dipping