If you want to remove the membrane from the bottom of the ribs, carefully remove it. Rub the ribs generously with the pork rub, making sure to rub the seasonings into any creases.
Place the seasoned ribs in a large baking pan and cover with foil.
Bake for about 2 hours, covered, at 275F. Add up to 30-60 minutes if your ribs are large or extra thick.
While the ribs are baking, mix together the maple syrup and apple cider vinegar in a small bowl.
Remove ribs from the oven, increase the oven temperature to 375F, and remove the foil from the baking pan, being really careful not to burn your fingers or face from the steam.
Brush the ribs with the maple syrup+apple cider vinegar mixture, then place them in the oven uncovered for 5-7 minutes.
Repeat Step 7 two to three more times, or until the ribs are nicely browned and caramelized.
Notes
Removing the membrane helps make fall-off-the-bone ribs, but I find that when ribs are roasted at a low temperature for 2 hours, they come out tender and break apart easily even without removing the membrane.