Preheat the oven to 325˚ and set a wire rack on a rimmed baking sheet.
Put the cumin and coriander seeds in a resealable plastic bag and crush with a heavy skillet. Transfer to a bowl and add the brown sugar, paprika and red pepper flakes. Season the ribs generously with salt and pepper, rub all over with the vegetable oil, then rub all over with the spice mixture, pressing to adhere. Transfer the ribs meat-side up to the rack.
Stir together the honey and vinegar in a small bowl. Bake the ribs, rotating the baking sheet after 45 minutes, until well browned, 1 hour 30 minutes to 1 hour 45 minutes. Brush half of the honey mixture on both sides of the ribs and bake 15 more minutes, then brush with the remaining honey mixture and continue baking until the ribs are deeply browned and tender, about 15 more minutes. Transfer the ribs to a cutting board and let cool slightly before carving.