Set the pellet grill temperature to 325 °F and preheat, lid closed for 15 minutes.
In a small bowl, combine the lemon zest, lemon juice, softened unsalted butter, dill, parsley, sea salt, and ground black pepper.
Generously coat the top of the salmon fillet with the mixture and top with a slice of lemon. Allow Marinate for about 10 minutes or so to absorb the mixture.
Place the salmon fillets on the hot grill grate, skin-side facing down.
Cook the salmon for 20 to 25 minutes, until it reaches an internal temperature of 145 °F and flakes easily, or until the salmon is cooked to your preferred taste.
Serve with lemon slices. Enjoy!