Preheat the grill to 225 degrees with an indirect heat. For gas grills, turn off the center burners. For a kamado grill, add a plate setter.
Rinse and pat the fillet dry before sprinkling on a little bit of sea salt.
Add a fruit wood to the grill or another mild option like alder.
Place the fillet on a copper mat on the grill.
Allow the fish to smoke until the internal temperature reaches 145 degrees.
Remove the rockfish and allow it to cool. Wrap it in saran and let it rest in the refrigerator overnight. The flavors will intensify as it is tightly wrapped.
Notes
Wrapping: I tried the fish straight from the grill and after it was wrapped the next day. I felt that wrapping it allowed the smoke flavor to permeate throughout the fish even more.Copper Mat: Using this is optional, but it is a game changer for my grilling. It provides a smooth (non-stick) surface for the fish and is super easy to clean up. I find it is really good for smoking and I didn't have to worry about any of the fish flaking and falling between the grates.