This recipe came out of necessity: to preserve tuna a friend brought me that no one ever thought he would catch. Plus, I liked the idea of putting something other than smoked salmon on my bagel in the morning. There are two things you need to know before cooking this bacon. First, you are cold smoking this fish—applying smoke flavor but not looking to cook the fish at all—so be mindful of your smoker temperature. Second, the tuna you buy should be part of the loin that is closest to the head. Tuna is a fast, strong fish with a lot of muscle and very little fat. Any fat it has is closer to the head. Now, tuna does have a belly, but I don’t use it for this bacon. I take my fillets, apply a little smoke, et voilà: tuna bacon!