So, back to canned tuna... First, let's talk about what you can buy in the store and for how much.
- Tuna packed in water -- that's not even worth talking about. This stuff is inedible in my opinion.
- Cheap tuna (such as albacore) packed in oil. Some of this stuff is fine in a typical tuna salad where it's mixed with mayo or vinaigrette type dressing. It's still relatively dry and crumbly, but not bad.
- Expensive tuna (such as yellowfin) packed in oil. This stuff is often imported and does taste good enough to eat out of a jar with no dressing. The problem is the price. 8 oz jar can cost $11. That's like paying $22/Lb for tuna, which is even more than upscale fish mongers charge for raw yellowfin tuna. For that price, I'd rather be eating tuna raw or seared medium-rare.
"What do you think of this package?" I asked Jason. "It's ok," he said hesitantly, "but what about this connective tissue?" Most tuna steaks butchered the European way have some chewy parts where connective tissue is thick. When tuna is butchered the Japanese way, the loin is divided into sections to provide consistency of texture, but that's hard to come by even at upscale fishmonger shops, let alone at Costco. "Don't worry," I told Jason. "I'll sear the good part medium rare and will poach the rest in oil for sandwiches and salad." "You mean like canned tuna?" he asked. "Yes, only sous-vide."
Jason has learned that if I mention "sous-vide," it's going to be good. And truth be told, I am yet to have a sous-vide disaster. The texture almost always surpasses conventional cooking methods. If you are new to sous-vide, here is the summary -- put food in a vacuum sealed bag and hold in a water bath at a precise doneness temperature (140F for tuna) for about 2 hours per inch of thickness (more about sous-vide).
For all practical purposes, poaching tuna in oil is kind of like making duck confit. Normally, you need enough fat in the pot to submerge the meat. I always found it kind of wasteful, especially when it comes to fish because that oil is not reusable. But using sous-vide method, I could get away with a very small amount of oil (about 1/4 cup) since I was sealing it in a bag with tuna. The problem is how do you seal a liquid without breaking your vacuum sealer? You freeze it first. The day before I was going to cook the tuna, I poured the oil into a vacuum bag and carefully placed it in the freezer trying to keep the oil relatively flat, but tilting the opening of the bag up so that the oil doesn't spill. Next day, I had a nice sheet of frozen oil.
I also decided to salt my tuna about 4 hours before cooking to make sure it's flavored throughout (like you would with duck, but for a shorter period of time). Then I put the tuna in a bag with frozen oil, vacuum sealed it, and put into my humongous beer cooler filled with 143F water. It dropped to 140F in about 15-20 minutes after the cold tuna went in. I kept it there for 2 hours making sure the temperature never dipped below 135F. And ta-da! I made my own canned tuna. Only way better. This stuff is not crumbly or dry. It's luscious! Just melts in your mouth. Not even the expensive imported canned tuna from Italy can compare to my home-made version. The only thing I'd do differently next time is use a light olive oil. Extra virgin is a bit too strong and overshadows tuna's flavor. Unfortunately, this stuff is perishable, but it should last for a week in the fridge as long as you keep it covered in oil. Maybe even longer, but a week is definitely safe.