Rinse the ribs and pat dry. Remove thin white membrane if the ribs still have it attached. See photo above. Flip the ribs over, meat-side down. Wiggle a dull knife (such as a butter knife) between the membrane and the ribs to loosen it. With a paper towel, grip the membrane and pull it away, then discard.
Mix rubs ingredients together in a small bowl. Rub it all over the ribs, generously coating all of the sides. Can do this step the night before or let it sit for 15-20 minutes to infuse the flavors (optional).
Place the trivet (or rack) in the bottom of a 6-quart or larger Instant Pot. Pour in the water, apple cider vinegar. Place the ribs inside the pot, standing them on their side.
Cover and seal the Instant Pot. For baby back ribs: Cook on high (manual) pressure for 30 minutes. No need to let it naturally release. It's cooked as is!
Towards the end of the ribs’ cook time, place a rack in the upper third of your oven and set it to broil. Line a large baking sheet with aluminum foil. Transfer the cooked ribs to the foil, then brush liberally with barbecue sauce. Place under the broiler just until the sauce begins to caramelized, about 2-3 minutes or directly on the grill. Do not walk away to make sure the ribs don’t burn.