Rinse and pat dry chuck roast. Sprinkle the entire outside with kosher salt and place in a large bag (Ziploc or roasting bag), then place in a bowl with the top open. Combine the salsa and barbecue sauce and pour into the bag with the roast. Gently massage to cover the meat in the sauce—marinate in the refrigerator for at least 24 hours, preferably 1-2 days in advance.

Preheat Instant Pot on manual, high pressure. Place the roast in, along with the marinade and 1 cup of beef or other stock. Cook on high for 60 minutes. After an hour, allow for a 20 minute natural release, then remove the lid and set Instant Pot to simmer. Simmer the beef and liquid for 20 minutes or so, or until the sauce has reduced and thickened and the beef is tender.

Remove the beef from the pot and set into a bowl or large plate. Use two forks to shred the beef, then return it back to the thickened sauce. Serve on buns, or on a sweet potato with cheese and herbs.