Whisk together all ingredients for the dry rub until fully incorporated.
Cut brisket into 3-4 equal pieces, then season the brisket with the dry rub mixture, making sure it's applied liberally and applied to all sides.
Add the butter or oil to the Instant Pot, and turn to "saute" mode.
Once hot, add the beef to Instant Pot in two batches, searing brisket for 3-4 minutes per side until browned, then remove from pot. Note: searing the beef all at once will cause overcrowding and will prevent the beef from browning nicely.
Once all beef is browned, pour in the broth and scrape the browned bits on the bottom with a whisk, then add the beef back to the pot.
Close the instant pot, making sure the valve is set to "sealing" rather than "venting." Set to cook on high pressure for 70 minutes.
Once the brisket is finished cooking, let the Instant pot release pressure naturally (about 15 minutes) until the lid easily opens.
Slice the beef against the grain and serve with BBQ sauce. Garnish with sea salt and cilantro, if desired. Enjoy!