Make sure the mackerel is very fresh. Filet the fish (or have it done at the shop). If there is any blood on the filet, gently pat it off with a paper towel.

Thoroughly rub salt over both sides of the filets. Let rest in the refrigerator for 2 hours. After 2 hours, was off the salt and pat dry. Note: Salting the fish is also important for making sure any bacteria is killed so make sure you let it rest the entire 2 hours.

Put vinegar, kombu and saba in a ziplock or plastic bag (The vinegar should cover the fish). Let marinade for 30 minutes (If you like more vinegary pickled flavor, let it marinade for longer time, up to 2 hours). Remove from marinade and carefully peel off the thin layer of skin, starting from the head-end of the fish. Cut into thin slices and serve. Serve with wasabi and/or soy sauce for dipping.