01 - Preheat oven to 400°F. Line a baking sheet with parchment paper or lightly grease it with cooking spray.
02 - Pat salmon fillets dry with paper towels. Place fillets skin-side down on the prepared baking sheet and season lightly with salt and pepper.
03 - In a small bowl, whisk together the maple syrup, whole-grain mustard, and fresh lemon juice until well combined. Brush the mixture generously over the top of each fillet.
04 - In a separate bowl, toss the chopped pistachios with the thyme. Press the mixture evenly onto the glazed surface of each fillet, pressing gently so the crust adheres.
05 - Bake for 14 to 18 minutes, or until the salmon flakes easily with a fork and the pistachio crust is golden brown. Cooking time may vary depending on the thickness of the fillets.
06 - Remove from the oven and let the salmon rest for 2 minutes. Serve with lemon wedges and a sprinkle of fresh dill or parsley if desired.