Preheat a large cast-iron skillet over medium-high heat for about 3 minutes.

Add the butter to the hot skillet, swirling to coat the pan evenly. Place the salmon chunks in a single layer in the pan and sprinkle lightly with kosher salt.

Sear the salmon for 2 to 3 minutes, or until a golden crust forms. Flip each piece and cook for another 2 to 3 minutes, until browned on both sides and just cooked through. The fish should flake easily with a fork when done.

Serve immediately and enjoy!