For us, crispy skin, either fish or chicken, is the best part. One of the great American sushi creations is called “salmon skin roll” using grilled or toasted crispy salmon skin in a small roll. The only way to make skin crispy without over cooking the fish is to cook the skin and fish separately. Here I removed the skin from a salmon fillet and cooked it separately with a good result.
The fish part was marinated in a sweet miso “saikyo miso” 西京味噌 (same amount of miso and mirin, heat to make marinade and cool to room temperature). This is a very similar marinade in Mark’s book “Sweet miso marinated fish 魚の西京漬け” (p61). I marinated for 30 minutes but you could go longer. The longer you marinate the more intense the miso flavor will become. You have to dicide how long is to your liking. I will marinate longer when using white meat fish without its own strong flavors such a cod. After 30 minutes, I remove the miso marinade, wash and pat dry. Then put the fish on a metal grate with a pan undereath and place them in a 350F oven from 10-15 minutes or until done (or you could also grill it).
Meanwhile, I salt the salmon skin and place on a non-stick frying pan (no oil needed) and put an identical sized frying pan nested on top (I cover the bottom of the top pan with aluminum foil so that I do not have to clean both pans). I suppose you could use a brick wrapped with aluminum foil but I have not tried it. On low-medium heat, cook 5-7 minutes and then turn the skin over for another 5 minutes or until the skin is very stiff and crispy.
I served this with simply boiled small green beans. We loved the skin more than the fish itself.