Optionally, brine the salmon for 15 minutes in 1/2 C salt and 2 qts water. Remove and pat dry.
Sprinkle salt in a non-stick skillet, then place the salmon skin-side down in the skillet and season to taste.
Heat the skillet over medium-high heat and cook the fillets without moving them until the fat begins to render, the skin begins to brown, and the bottom 1/4-inch turns opaque.
Flip the fillets, add 1 T butter, and continue cooking without moving them until the centers are opaque and register 125 degrees.