Just because the most popular recipes for slow-cookers are soups and stews doesn’t mean you can’t do way (way!) more with the appliance. Case in point: slow-cooker tuna confit. Okay, technically to “confit” means to slowly cook something in its own fat, such as duck or chicken, but sometimes we bend definitions. This tuna confit calls for a thick piece of tuna to take a long, luxurious bath in olive oil under the gentle heat of a slow-cooker. Just as the device slowly transforms soupy situations over hours, it will delicately cook a piece of fish (in less than an hour). The process itself is relatively hands-off—just add the fish to the slow-cooker after heating aromatics in oil. While the tuna’s taking care of itself, you’ll have time to prep the lemony mayo and gather any other accoutrements. But if you prefer to serve the fish more simply, say, over a bed of greens, you can just pour yourself a glass of wine and let dinner do its thing.
Note: If your slow-cooker is larger than 4 quarts, you’ll need more oil—at least ½ cup more per additional quart capacity of your slow-cooker—and the tuna will likely cook about 5 minutes faster than the instructions note. (Reverse that if your cooker is smaller than 4 quarts.) To make this recipe without a slow cooker, swap in a heavy bottom pot, such as a Dutch oven. In Step 1, cook over medium-high heat; in Step 2, cook over medium-low heat until the tuna comes up to temperature.
Now that you’ve given tuna a whirl, how about cooking a whole dang squash or a massive chocolate chip cookie in your slow-cooker? —Rebecca Firkser
- Prep time 15 minutes
- Cook time 40 minutes
- Serves 4
- Slow-Cooker Tuna Confit
(8-ounce tuna) fillets, such as ahi, albacore, or yellowfin, each about ¾ to 1 inch thick
Kosher salt and freshly ground black pepper
1 3/4 cups
extra-virgin olive oil, plus more as needed
garlic cloves (5 smashed and peeled, 1 finely grated)
Handful fresh thyme sprigs
red pepper flakes (optional)
- For Serving
capers in brine, drained
kalamata or ¼ cup oil-cured black olives, smashed and pitted
7-minute boiled eggs, halved or quartered (optional)
Fresh basil and/or parsley leaves
Toasted country bread or baguette
- Place the tuna on a small sheet pan or dinner plate; season both sides with salt and pepper. In a 4-quart slow-cooker, combine 1¾ cups of oil, the smashed garlic, thyme, and red pepper flakes (if using). Cover and cook on high for about 20 minutes, until warm and fragrant, then turn off the slow-cooker.
- Use an instant-read thermometer to check the oil’s temperature (it should be around 130°F). Gently place the tuna in the slow-cooker. If the tuna isn’t covered (this will likely happen if the fish is on the thicker side), add more oil until it is. Cover the slow-cooker and cook on low for 20 to 30 minutes, until the tuna is opaque and flakes when pulled with a fork and comes up to your preferred temperature (125°F to 130°F for medium-rare and 145°F for well-done). Gently pick up the tuna with a fish spatula and transfer to a serving platter. Using a spoon, gently break up the flesh into large, uneven pieces.
- Transfer the oil to a heatproof bowl and let cool. Once cool, strain through a fine-mesh sieve and store in an airtight container in the refrigerator. Use the strained oil for cooking or salad dressing for up to 3 months. (You can also pluck out the garlic cloves from the strainer if you want to smear them on bread or chop and stir into pasta or salad dressing—store them submerged in the oil for up to 1 week.)
- In a small bowl, combine the mayonnaise and grated garlic. Slice the lemon into wedges and squeeze 1 teaspoon of the juice into the mayonnaise. Season with salt and pepper and more lemon juice to taste.
To serve: Spread a hefty spoonful of the mayonnaise mixture onto each plate. Scoop on a few pieces of tuna, capers, olives, and an egg half or two; top with the basil or parsley leaves. Drizzle with some of the cooled tuna oil, if you’d like. Serve with a slice or two of toast and the remaining lemon wedges for squeezing over. (Alternatively, start with the toast, slather with mayonnaise, and build up from there for an open-faced sandwich.)
Do Ahead: The tuna can be made 1 week ahead. Store completely submerged in olive oil in an airtight container in the refrigerator.