1. Roast the salmon.

Heat oven to 400 degrees. Line a baking sheet with aluminum foil. Season salmon on both sides with salt and pepper. Place salmon skin side down on the baking sheet. (If your filet is skinless, place the fish with the gray side down.)

Slice the lemon into thin circles, discard the two end pieces, and place the remaining slices atop the salmon in a single layer. Drizzle 2 tablespoons of olive oil over the top. Roast until salmon flakes easily and is cooked through, 12 to 15 minutes.

2. Cook the fennel.

While the salmon is roasting, place the remaining 1/2 cup olive oil in a medium pot over medium heat. When oil is warm, place sliced fennel in the pot along with a big pinch of salt. Cook, stirring occasionally, until fennel is cooked al dente, about 12 minutes. The fennel shouldn’t brown or sizzle — this cooking method slowly softens the fennel without crisping or caramelizing it.

When fennel is cooked, stir in the parsley. Use a slotted spoon to remove the fennel and parsley from the olive oil. (You want everything coated in a bit of oil but not swimming in it.) Place it on a large serving platter.

3. Serve.

When salmon is cooked, let it sit on the baking sheet for a few minutes, then use a long metal spatula to place it atop the fennel on the serving platter.