If the brisket has not already been trimmed for you, trim the fat cap to remove any hard pieces of fat. Pat the brisket dry. Season as liberally as you dare with Montreal steak seasoning.
Spread the dry rub evenly on the meat. Pat the rub down to ensure that it adheres well.
Turn the brisket over so it is fat cap side up. Season this side with seasoning as well.
Season the sides of the brisket with the Montreal Steak seasoning, and set aside.
Add the rack to the Instant Pot.
Add the seasoned brisket into the Instant Pot on top of the rack.
Slice the onion, and add to the pot on top of the meat.
Pour in the beef broth on top of everything. Seal the lid on your pressure cooker, and cook on high (normal) pressure for 70 minutes, followed by a full natural pressure release (around the thirty-minute mark on my IP-Duo 6-quart). Once done, remove the lid and put the brisket on a plate or platter with the rack.
Slice the brisket, and serve with gravy. Serve immediately or store in an airtight container for up to one week.
Video
Notes
If doubling the recipe just with any other pressure cooker recipe, you will not need to increase the time. You don't necesarily need to increase the liquid unless you would like more gravy either.If you would like some gravy, then remove the meat, vegetables, and rack from the pot. Set the Instant Pot to saute mode to heat up the broth to make gravy. Once it's heated up, add your cornstarch slurry to thicken! If you would like it thicker, do another round of this.Slice your brisket against the grain so the meat is tender. Cutting against the grain means cutting perpendicular to the muscle fibers when slicing. Cutting the meat like this ensures smaller muscle fibers, which make the bite more tender.