This is basically a rustic pantry pasta sauce turned flavor-bomb condiment, and it's pretty versatile: It works as a dip (think bagna cauda or pinzimonio); or tossed with pasta and a little of its cooking water; or to sauce a plate of seared wax beans and assertive greens (such as arugula). I think it would also be the cat's pajamas spread on an open croissant, topped with sliced tomatoes and cheese, and put under the broiler to make an upscale tuna melt.
The trick is in cooking the jarred tuna with a heady mix of alliums, herbs, aromatics, and white wine. Like broccoli and cauliflower, its cruciferous cousins, radish has a natural affinity for anchovies and butter, so those get thrown into the mix as well. The result is complex and deeply flavorful even before it hits the food processor. Don't forget to reserve the oil the tuna was packed in for adding the pureé later. It adds yet another dimension of flavor. —Chris Hagan
Test Kitchen Notes
This recipe yielded an elegant crostini topping for a dinner party, and then a weeknight pasta sauce. There are a lot of ingredients, but it comes together pretty quickly. A few things I might do differently next time: Use more anchovies—like, the entire can. I would have cooked it down a little more, because when I puréed the mixture, I was hoping for a spreadable paste, but got a looser, chunkier sauce. That was perfect over pasta with a sprinkling of chopped parsley the next day. It does make a lot, so I will be thinking of another use for the leftovers later this week. —Deborah B.
4 to 6
unsalted butter, divided
small yellow onion, finely chopped
fennel bulb, trimmed, cored, and diced
4 or 5
(1 small handful) spring radishes, trimmed and diced
hot pepper flakes (or more to taste)
garlic cloves, minced
6- to 8- ounces
can (or jar) good-quality tuna in olive oil, drained and chopped, oil reserved
dry white wine
capers, drained and rinsed
Italian parsley leaves, finely chopped, plus extra for garnish
mayonnaise or aioli
2 to 4 tablespoons
red wine vinegar or lemon juice (start with 2 and adjust from there—I prefer more tang)
Heat the olive oil and 2 tablespoons of the butter in a skillet or saucier. Add onion, fennel, and radishes, and sauté on medium-low heat until tender and translucent. Add hot pepper flakes, garlic, and anchovies and continue sautéing over medium-low, until the anchovies have dissolved, and then stir in the tuna, mashing with the back of a wooden spoon to break up any large chunks. Raise the heat to high and add the wine. Cook until almost all evaporated, then lower the heat and stir in the capers and parsley. Swirl in the remaining 1 tablespoon of butter and remove from heat.
Allow to cool slightly, then transfer to a blender or food processor. Add the mayonnaise (or aioli), vinegar (or lemon juice), reserved tuna oil, and water, and process until smooth. Then let it go some more, until it is super light and airy. (You can also do this directly in the pan with an immersion blender.) Adjust for salt, pepper, acid, and—if you prefer a little extra zip—hot pepper. You may need to add a little more olive oil or water if the purée is too thick. Serve as a dip, or tossed with pasta and a little pasta water (and something assertive and green, like arugula), or as a crostini topping, garnished with chopped parsley. [Editors' note: We spread the tonnato on a plate, then topped it with boiled potatoes, blanched asparagus and snap peas, and raw radishes and Romanesco.]