Preheat the oven to 325°F (160°C).
Get a 9X13 baking dish out and coat with non-stick cooking spray. Layer the sliced onions on the bottom and add in the stock. Set aside.
Remove the ribs from the package. Pat dry with paper towels and remove the membrane from the back side of the ribs (the easiest way is to peel about ½ inch away with a knife, then grab with a dry paper towel and pull. It should come right off!)
Slice the rib rack in half. Coat all surfaces with the dry rub. If you run out of rub, make some more.
Heat the skillet over medium-high heat and add the oil. When the pan is nice and hot, begin searing the ribs and the meat side down. They should cook for about two to three minutes in the pan. Get them nice and brown! You do not need to sear the bone side. As they get browned, remove from the pan and layer in the prepared baking dish.
While the pan is still hot, deglaze with ½ cup cold tap water. Stir constantly to get the brown bits off the pan. Pour the water from the pan directly into the 9X13 baking dish.
Cover the baking dish with aluminum foil and make sure the foil has a good seal. Put the dish in the oven and cook for 2 hours.
This is a great time to make the Super Easy BBQ Sauce Recipe.
We want the ribs to be about 200°F (93°C). When they are done, remove them from the oven, remove the aluminum foil, and let them sit for about 15 minutes. This is a great time to start the grill.
When your grill is hot, use a pair of tongs to put the rib bone side down on the grate. Slather your favorite barbecue sauce over the top and close the lid. Cook for 3-5 minutes, then flip and repeat. Cook for another 3-5 minutes and flip to caramelize the barbecue sauce a bit. Flip back and lightly dab more sauce on. Your delicious, juicy baby back ribs with barbecue sauce are now ready to be devoured.