Light just one or two burners on your gas grill so you can cook the ribs over indirect heat. You want a temperature of about 300F. (If you use a charcoal grill, after lighting the briquettes, move them to one side of the grill and keep the fire as low as possible. You'll probably need to add more briquettes every hour.)
Mix all the dry ingredients together, then rub on the ribs.
Put the ribs on the grill where they are not over direct heat.
Turn the ribs every half hour or so. Cook for 3 hours or longer... Make sure the heat is low if you cook longer.
Just before serving move the ribs over the heat and brown on each side just a few minutes.
Serve with your favorite barbecue sauce.