Remove 1/4 cup of the liquid from the jar of sweet peppers and add to your electric pressure cooker. Drain the remaining liquid and seed and chop the peppers. Add the peppers to the pressure cooker along with the onions, garlic, beef broth and Worcestershire sauce.
Rub the beef roast with garlic salt and add to the pot. Cook on high for 65 minutes. Using a 10 minute slow release, open the pressure cooker.
Remove 3/4 cup of the liquid and discard or refrigerate for another use. Remove the roast from the pot and place on a large cutting board. Using two forks, shred the beef into small pieces. Return the shredded beef to the pressure cooker and stir into the liquid. Serve immediately or allow to cool and store refrigerated in an airtight container.
*My personal favorite, is to serve the hot beef on fresh buns with Dijon mustard.
NOTE: If you are using an Instant Pot larger than 6 quarts, you will need to add more liquid to meet your pot's minimum liquid amount.