Here, you will need to use dry brine ingredients, which are:Canning or kosher salt – 5 lbs.Dark brown sugar- 6 lbs.
Mix the sugar and salt thoroughly with your hands so that you can break up any chunks in the brown sugar. You will use to dry-brine the fish. Make sure that you use kosher or coarse (non-iodized) salt. In case you have any leftover dry mix, place it in a ziplock bag or sealed container. This will preserve the mixture for future use.
Next, take a small container, long enough and with enough width that will allow you to lay your fillets flat, and spread an even ½” layer of the dry brine mixture on the container’s bottom. After spreading the dry brine mix, place your first fillet layer on top of the dry mix, when the skin side is facing down. Now, you can cover the fillets with extra dry mix ½” layer and then place the next layer of fillets on top, now with the skin side facing up. Cover the fillet with ½” layer of the dry mix, and make sure that the dry mix covers the fish completely. You should understand that the size of your container matters as it prevents you from wasting the dry brine mix.
Continue layering the fish fillet, and you can place them in the manner that you like, so long as they are somehow flat and straight. This process is essential as it removes any excess moisture in the fish, and makes it firmer.