Combine sugar, salt, paprika, pepper, thyme, garlic and zest.
Spread on a sheet pan and let stand at room temperature overnight so that the sugar is hard and dry.
Grind in a food processor to a fine powder.
Brush the ribs with oil and lightly coat with sugar mixture.
Place on a medium hot grill or grill pan, fat side down first, cooking 20-30 minutes per side until the meat is just coming off the bone.
Slice into individual ribs and serve.
Servings: 4