1 slab St. Louis-style ribs, membrane removed
½ cup water
Kosher salt
Freshly-ground black pepper
½ cup barbecue sauce, plus additional for serving if desired
Place the trivet in the Instant Pot.
Season the ribs generously with salt and pepper. Place them on top of the trivet in the Instant Pot and add the water.
Close the lid and turn the valve to the sealing position. Select high pressure and set the timer for 30 minutes.
When the cooking time is up, let the pressure release naturally for about 15 minutes. Quick release any remaining pressure.
Remove the ribs from the pot and reserve the cooking liquid.
In a small bowl, whisk together the barbecue sauce and ¼ cup of the reserved cooking liquid.
Preheat the broiler or grill to high heat.
Brush the ribs all over with the sauce mixture. If planning to broil them, arrange them, meat side up on a large, rimmed baking sheet that has been lined with foil.
Place the ribs under the broiler or on the grill. Cook until the sauce bubbles and thickens, 5 to 6 minutes. Brush again with the remaining sauce mixture and cook for another 2 minutes or so.
Serve hot with extra barbecue sauce, if desired.