Step 1Using a sharp paring knife, cut tiny slits into the meat of the ribs and place the ribs in a shallow dish. Combine the salt, 1 1/2 teaspoons cayenne and the lime juice and rub into the meat on both sides. Set aside at room temperature for 20 minutes.
Step 2Combine the mustard, cumin and coriander seeds in a small skillet over medium heat and cook just until the mustard seeds pop and the others release their fragrance. Transfer to a blender and add the yogurt, garlic, ginger, turmeric and remaining cayenne. Process until smooth. Pour over the ribs and turn them to coat, top and bottom. Cover with plastic wrap and refrigerate overnight.
Step 3Heat the oven to 350 degrees. Lift the ribs from the marinade and lay them on a rack in a baking dish, flesh side up. Spoon the remaining marinade over the ribs, spreading evenly. Bake 30 minutes, then turn the ribs over and cook 30 minutes longer.
Step 4Heat the grill. Brush the rack lightly with oil. Remove the ribs from the oven and place on the grill, flesh side down. Cook until charred and crisp on both sides, about 15 minutes total.