Inspired partly by the Altoona Tuna Melt at the former Sidetracks in Fairfield, CT (as well as local burger chain Duchess' Big D Tuna), partly by New England-style fish cakes, and partly by a desire to see what happens when you treat salsa tonnato like pancake batter, I came up with these patties. I like them slider-size, but feel free to go big or go home. These can be eaten burger-style on a bun (or try them in a croissant, if you're feeling decadent)--suggested toppings include melted cheddar, or tomato, or something green like Bibb lettuce, arugula, or watercress--or as is, with some lightly dressed greens. —Chris Hagan
unsalted butter, divided
small yellow onion, chopped
small fennel bulb, chopped
handful of spring radishes (5 or so), trimmed and chopped
hot pepper flakes, or to taste
generous pinch of caraway seeds
garlic cloves, chopped (remove and discard any green shoots)
big handful of Italian parsley leaves, chopped (to yield a 1/4 cup or so)
6-8 oz cans good-quality tuna in olive oil, darined and chopped, oil reserved
Heat the olive oil and 1 tbsp of the butter in a large skillet over medium-low heat. Add onions, fennel, and radishes, and saute until tender and translucent. Add pepper flakes, caraway, garlic, and anchovies, and continue sauteing until anchovies have dissolved, 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 the parsley. Stir in the remaining tbsp of butter and remove the pan from heat. Let the mixture cool completely.
Transfer half of the skillet mixture to a food processor with the mayonnaise (or aioli), vinegar (or lemon juice), and water. Measure out and add 2 tbsp of the tuna oil, discarding the remainder. Pulse until you achieve a pasty consistency. Transfer to a mixing bowl and lightly mix with the remaining skillet mixture. Refrigerate several hours or overnight.
When you are ready to cook, form the mixture into patties of roughly equal size and heft. I think slider-size is ideal, but feel free to go big. Heat a large non-stick skillet and slick with a light coat of olive oil. When it shimmers, add the patties in batches, taking care not to overcrowd. Pan-fry until browned, then flip and cook until heated through. Serve on mini-brioche buns, or better yet, mini croissants, perhaps with some arugula or watercress and a little cheddar melted over. (Do this open-faced for tuna melt-style.)