Start by removing the membrane on the back of the ribs.
Next, cut between each bone so that you have separated all of the ribs.
Pat dry with paper towels and set them in a large bowl.
Sprinkle with the salt and ground black pepper; massage each individual rib so that each one is well seasoned.
Next, ensure a trivet or steam rack is in the instant pot; pour in the stock and vinegar.
Lay the ribs onto the steam rack in a random fashion; close and seal the instant pot; pressure cook on high for 23 minutes.
Once done, allow the steam to release naturally for five minutes; then, carefully open the valve to let remaining pressure out.
In the meantime, prepare the sauce by placiing all of the sauce ingredients, except the sesame seeds and green onions or chives, into a container with a tight lid; whisk well to combine; set aside.
Transfer the ribs to the bowl with the prepared sauce; gently toss to coat; be careful as the ribs are already very tender; try to keep the bone in the meat to make grilling easier.
Pre-heat grill to 450°F.
Once the grill is hot, place each rib onto the grill and allow to cook undisturbed for 2 to 3 minutes.
While they cook, use a pastry brush to baste the ribs.
Carefully flip the ribs over using tongs and cook for 2 to 3 minutes more; baste the ribs once again.
Once satisfied with the grill marks, get the ribs off the grill.
Garnish with sesame seeds and green onions or chives; serve immediately.