When ready to cook, set the Traeger temperature to 350°F and preheat with the lid closed for 15 minutes.
In a small bowl, mix together the butter, lemon zest, lemon juice, dill, salt, and pepper.
Generously slather the top of each salmon fillet with the lemon-dill butter. Top each fillet with a lemon slice.
Insert the probe horizontally into the center of a salmon fillet. Place the fillets, skin-side down, directly on the grill grates. Cook until the internal temperature reaches 130°F for medium-rare, 15-20 minutes, or to your desired temperature.
Remove the salmon from the grill. Garnish with more dill and serve. Enjoy!
