Place the ribs on a foil-lined rimmed baking sheet. Sprinkle with salt, cover with another piece of foil, pressing down around them to tightly cover the ribs, and bake for about 3 hours until the ribs are very tender. If you like, pre-cook the ribs up to this points, cool and refrigerate for up to 3 days; finish in the oven or on the barbecue.
Meanwhile, combine the spices in a small dish.
Uncover the ribs, turn the heat up tp 450°F (or preheat the barbecue to medium-high), sprinkle the ribs generously with the dry spice mixture (rub it all over the surface with your fingers if the meat is cool enough) and bake or grill for 10-20 minutes, until the ribs have darkened and the edges are caramelized.