1 ¼ lb fresh tuna, diced2 scallion, thinly sliced12 pitted Kalamata olives, coarsely chopped1 Tbsp salted caper, rinsed and minced salt and freshly ground pepper extra-virgin olive oil, for brushing¼ cup mayonnaise1 ½ tsp anchovy paste4 brioche bun, split and toasted sliced tomato, for serving arugula, for serving
- Spread the tuna, scallions, olives and capers on a plate and freeze for 5 minutes. Transfer to a food processor and pulse until the tuna is finely chopped. Transfer the mixture to a bowl; season with salt and pepper. Form the mixture into four 4-inch patties.
- Light a grill or preheat a grill pan. Brush the burgers with olive oil and grill over moderately high heat, turning once, until golden and crusty and just cooked through, about 6 minutes.
- In a bowl, mix the mayonnaise and anchovy paste; spread on the buns. Top with the burgers, tomato and arugula, close and serve.