Fill the bowl about 1/2 inch high with salt. Place the breasts onto the salt, skin side up. Make sure they don’t touch, then pour more salt between them until they are covered. Cover with plastic wrap and put into the fridge for a minimum of 24 hours, but no longer than 36.
Take the breasts out of the salt. The colour will be a deep red and the meat will feel dense. Wash the salt off the meat with cold water, then pat dry with a paper towel. Rub the meat side with the spice mixture and wrap them into a layer of cheese-cloth. Hang into a cool, dark room for 7-10 days. If they aren’t completely dried and stiff feel squishy and raw, dry for a day or two longer.