Step 1

Arrange a rack in the middle of the oven and heat the oven to 425°F. Meanwhile, marinate the salmon and make the sauce.

Step 2

Mince 2 garlic cloves and place in a baking dish large enough to fit the 4 salmon fillets in one layer with a bit of room in between each piece. Halve 1 medium lemon and squeeze the juice from one half into the baking dish. Add 2 tablespoons olive oil, 1/2 teaspoon of the kosher salt, and 1/4 teaspoon of the black pepper, and whisk with a fork to combine. Add 4 salmon fillets, turning them over gently a few times to evenly coat in the lemon-garlic mixture. Arrange in a single layer skin-side up if there is skin. Cover and refrigerate.

Step 3

Squeeze the juice from the remaining lemon half into a small bowl. Set aside a few fresh dill sprigs for garnish if desired, then finely chop more dill until you have 2 tablespoons. Add the chopped dill, 1/2 cup sour cream, 1/2 teaspoon Dijon mustard, the remaining 1/4 teaspoon kosher salt, and the remaining 1/4 teaspoon black pepper to the bowl and whisk to combine. Refrigerate until ready to serve.

Step 4

When the oven is ready, uncover the salmon and roast until cooked through and easily flaked, 8 to 12 minutes. An instant-read thermometer into the middle of the thickest fillet should register 120°F to 130°F for medium-rare, or 135°F to 145°F if you prefer it more well-done. Serve topped with the creamy dill sauce. Garnish with fresh dill sprigs and serve with lemon wedges, if desired.