1Tblsgrated lemon zest, plus 3 tablespoon fresh lemon juice
12.5 lbside of salmon skin on or off
2 3/4tspkosher saltdivided
3/4tspblack pepperdivided
1/2cfinely chopped fresh flat-leaf parsley
1/4cwalnutstoasted and finely chopped
1/4cChampagne vinegar or white wine vinegar
1/4cpitted kalamata olives, chopped about 1/3 c
1/4cpitted Castelvetrano olives, chopped about 1/3 c
Instructions
Preheat oven to 325°F with rack in middle position.
Whisk together 1/2 cup oil and paprika in a small bowl. Set aside 1 tablespoon oil mixture; stir lemon zest and juice into remaining oil mixture in small bowl.
Place salmon in a large baking dish; sprinkle both sides (if skin is removed or skinless side if not) with 2 1/2 teaspoons salt and 1/2 teaspoon pepper. Tuck tapered end of salmon under if needed to fit in dish. Pour lemon-paprika mixture over salmon. Bake in preheated oven until thickest part of salmon flakes easily with a fork, 30 to 35 minutes, spooning lemon-paprika mixture in baking dish over salmon every 10 minutes. Remove from oven; let rest 5 minutes.
Meanwhile, whisk together parsley, walnuts, vinegar, olives, and remaining 1/4 cup oil in a small bowl. Season with remaining 1/4 teaspoon salt and remaining 1/4 teaspoon pepper.
Using 2 large spatulas, carefully lift salmon from baking dish, and transfer to a large platter; discard remaining lemon-paprika mixture in baking dish. Spoon walnut-olive vinaigrette on salmon. Drizzle fish with reserved oil mixture. Serve warm or at room temperature.
Notes
Vinaigrette can be made 2 days in advance and stored in an airtight container at room temperature.