Begin by rinsing the baby back ribs under cold water, then pat them dry carefully with paper towels. Remove the membrane from the back of the ribs to enhance tenderness. If needed, cut ribs into sections to fit.

Generously apply the dry rub to the ribs, ensuring it gets into every crevice. Massage the rub into the meat thoroughly and let sit for about 15 minutes.

Insert a trivet into the Instant Pot and pour in about one cup of chicken broth or water. Stand the seasoned ribs upright on the trivet, sprinkle the sliced garlic and onion over the top.

Close the Instant Pot lid securely, set the valve to sealing. Cook on high pressure for 22-26 minutes, depending on rib thickness. Allow for a 5-minute natural release before a quick release.

For a charred finish, preheat the broiler or grill to high. Remove ribs from the pot, brush with BBQ sauce if desired, and broil or grill for 3-5 minutes until caramelized.