For this dish, buy the thickest salmon fillets you can, remove all the skin (not as hard as it looks—just have a sharp knife handy), and broil it just until it’s warm all the way through.
Preheat the broiler. Lightly grease a baking sheet and set aside.
Pick stems from the spinach; discard bad leaves. Wash the spinach in several changes of water. Place the wet spinach in a large saucepan and cook, uncovered, over medium-low heat until wilted. Drain the spinach and set aside until cool enough to handle. Squeeze out excess water, coarsely chop, an