1 large cedar plank (big enough to fit the entire salmon fillet)
Soak a large cedar plank (big enough to fit the entire salmon fillet) in water for at least 30 minutes.
Set up your grill for indirect heat. If using a charcoal grill, build the coals on one side only. If using a gas grill, heat one side only. Allow the temperature to heat to 350 degrees F.
While your grill is coming up to temperature, prepare the salmon. Place the salmon skin-side down on the cedar plank. Brush the flesh side of the salmon with the mustard, then liberally season with the everything spice.
Place on the indirect heat side of the grill, close the lid, and cook until the salmon reaches an internal temperature of 125 degrees F, 20 to 22 minutes. Cook the salmon longer if you like it more done. Cut into slices and serve.
Oven method: Bake on a rimmed baking sheet at 350 degrees F until the salmon reaches an internal temperature of 125 degrees F, 20 to 22 minutes.