Place the salmon fillets, evenly spaced, in the middle of the prepared baking sheet. Sprinkle the tops with a pinch of salt and a few grinds of pepper. Bake until the outside is opaque and slightly firm to the touch and the inside flakes easily (insert a small knife between layers to check; the color will vary from bright pink (rare) to pale pink to orange (well-done), 8 to 12 minutes.

Remove the fillets from the oven, top each with a piece of butter and let melt over the top and down the sides. Sprinkle with herbs, lemon juice, and salt to taste. Transfer the salmon to serving plates with a spatula.