Preheat the Oven: Preheat the oven to 325°F (162°C). Set out a baking dish large enough to accommodate the salmon in one layer.
Prepare the Salmon: Lightly coat both sides of the salmon fillets with 1 tablespoon olive oil, then season with salt and freshly ground black pepper. If desired, cut the salmon into four approximately 6-ounce fillets. Build the Baking Dish: Arrange the lemon slices and 4 fresh dill sprigs across the bottom of the baking dish.
Arrange the Salmon: Place the seasoned salmon in the dish skin-side down, directly over the lemon slices and dill.
Add the Wine: Pour ½ cup dry white wine or water into the baking dish around the salmon.
Cover the Dish: Cover the baking dish securely with aluminum foil to create a gently enclosed cooking environment.
Bake the Salmon: Bake for 15 to 20 minutes, depending on the thickness of the fillets. Begin checking the fish after 10 minutes, since thicker pieces may require additional cooking time.
Check for Doneness: The salmon is ready when it flakes easily with a fork. For the most reliable check, insert an internal thermometer into the thickest part of the fish; it should register 125°F.
Rest the Salmon: Remove the baking dish from the oven, then loosen or untuck the foil so it covers the dish loosely. Let the salmon rest on the counter for 5 minutes, allowing it to continue cooking gently.
Finish and Serve: Scatter chopped fresh dill over the salmon and serve with some of the cooking liquid from the bottom of the dish if desired.