The technique is wonderful, even in Western preparations, and solves many of the problems home cooks have with salmon, namely spattering when searing, the potential to stick to the pan, and the struggle to keep the fish together. moist and juicy inside while developing lots of browning. flavor or crispy skin.
To get an idea, I bought several whole salmon at Pike Place Market (including coho, sockeye, and wild and farmed king). I evenly salted 5 ounce fillets with about 1 teaspoon kosher salt per fillet, then left them on a paper towel lined tray in the fridge overnight, uncovered. Then I compared them to fresh fillets cut from the same fish and seasoned with the same amount of salt just before cooking. Each was cooked skin side down with a little oil in identical pans heated to maintain a surface temperature of 390 degrees. I cooked all the salmon as I normally would: skin side down to an internal temperature of 100 degrees (or about medium-rare with a translucent center for salmon fillets), with a short stay on the second side for color.
From the start of cooking, there was a noticeable difference between fresh fillets, whose excess moisture caused a large amount of spatter, and dry-cured fillets, which seared with very little spatter. As the fresh fish cooked, drops of white protein began to collect on its edges, while the dry-cured salmon remained bright orange the entire time. Flipping the dry-cured fillets was also much easier than flipping fresh, and the dry-cured fillets reached their target internal temperature about 20% faster, with better exterior browning and crispier skin.
By weighing the salmon fillets before and after their overnight rest, as well as before and after cooking, I was able to determine how much moisture was lost and at what stage. It turns out that each salmon fillet lost 8-11% of its weight in moisture. So what is the difference?
With dry-brined fillets, most of this moisture evaporates during storage; only a small amount comes out during cooking. With fresh, on the other hand, all that moisture is pushed into the pan during cooking, where it then has to evaporate. This takes the heat away from the pan, which is why fresh fillets take longer to cook and don’t brown or be as crispy. As this water is expressed from inside the nets, protein goes along the way, coagulating into unsightly white specks on the surface of the salmon. Excess protein-rich moisture in the pan is also the culprit for excessive sticking and spattering.