Several years ago, a friend and colleague gifted me a bag full of salmon heads. I realize that, to many people, this may not sound like much of a gift, but I was excitedly racing to come up with ideas for what to do with them. Before I settled on an answer, my friend said, "You should make rillettes." It was a brilliant suggestion.
Rillettes (pronounced ree-yet) are a spread made from shredded meat or fish. Most common are pork rillettes, in which the pork is slowly cooked, confit-style, in its own fat until the meat falls apart at the slightest touch. It's then shredded and mixed with seasonings and plenty more of the liquid fat. Once it's slightly chilled, the fat firms up like butter, which results in a luxuriously silky texture, ready to be spread on toasts or crackers.
Fish, though, and salmon in particular, lends itself to the preparation as well, giving an otherwise rustic hors d'oeuvre a much more elegant appearance. The salmon heads that I had at the time were perfect for it because of how much of the fat is packed away in them. (Plus, there's a ton of meat, if you know where to look and are willing to dig and pick.*)
Start with the plump cheeks, then pull away the skin and search for meaty pockets around the eye sockets and on top of the head.
Even without salmon heads, though, you can still make excellent rillettes, which I'm guessing is good news to anyone who's been recoiling at the idea of dissecting the cranium of any creature, ichthyoid or not. The important thing is to use a fatty piece of salmon fillet, which in most cases means farm-raised fish, ideally with a good amount of the belly flap included—after all, that's the fattiest part. Most wild salmon is much leaner, making it a poor choice for rillettes, though, if you can get your hands on fatty wild salmon, that'd be a great option. (It's easy enough to tell by looking: Fatty fish has visible white fat, especially near the belly area.)
To make salmon rillettes, start with a boned, skinned fillet (or heads, if you want to go that route), and dice it for quick cooking and easy shredding. To cook it, I poach it in an aromatic, lightly acidic stock known as a court bouillon, though, honestly, you could use water here if you don't feel like dealing with the aromatics—it won't make a huge flavor difference in the end.
I like to start the fish in cold liquid, then bring it up to temperature gradually, which cooks the fish more gently than dropping it into boiling-hot water. I also try not to let the liquid get much hotter than about 170°F, which is more than enough to cook the fish; any higher and all you're doing is drying the fish out. Still, for this preparation, you have more room for error, since the salmon is ultimately shredded and mixed with other ingredients, so don't obsess too much about that.
Because the salmon pieces are small, they should cook very quickly once the water becomes hot, in a few minutes at most. Salmon is much easier than pork in this regard, since it takes so much less time to cook. (Pork has tougher connective tissue that needs to cook a lot longer before softening enough to allow for shredding, but fish is more delicate and, therefore, can be shredded from the start.)
As soon as the fish is just cooked through—which you'll know it is if you can separate the flakes of a piece with gentle pressure—it's ready to be drained. Then I transfer it to a mixing bowl and roughly shred the meat with my fingers. I try not to shred it too much, since it'll break down a lot more when it gets stirred with the ingredients added next.
Incidentally, if you've got a sous vide setup, bagging and cooking salmon for 25 to 40 minutes at 125°F will give you great rillettes-ready texture.
In go mayonnaise, minced shallot that I've cooked gently in butter, fresh lemon juice, chives, and a touch of spices, including a pinch of cayenne or another chili powder—not to make the rillettes spicy exactly, but just to give them a hint of heat. Given the use of mayo as the primary binder (aside from the fish fat), these rillettes are kind of like tuna salad, though the fresh salmon gives it a significantly different flavor from that imparted by canned tuna.
At this point, because the salmon is still warm, the mixture may look a little oily and broken. That's okay: Just transfer it to a ramekin or crock, cover with plastic, and refrigerate it for a few hours, until it's chilled. When it comes out, it will have thickened up and be ready for spreading...bag of fish heads not required.