Combine the beans, beef stock and ground beef in the pot of the pressure cooker.

Use a potato masher to mash the beans and ground beef to a very fine consistency.

Add the tomato paste, mustard, onion, chili powder, cumin, garlic, vinegar and Worcestershire sauce.

Place the lid on the pressure cooker and turn to locked position.

Turn the steam release valve to sealing.

Press the manual button and adjust the time for 5 minutes.

When the unit has finished cooking and the timer has counted to zero, carefully release the steam and remove the lid.

Stir well, taste for seasoning adjustment and add kosher salt as needed.

Stir in hot sauce if desired.