1 1/2 tablespoons fresh lime juice
Half of a 14-ounce can hearts of palm, drained and thinly sliced crosswise (about 1 cup)
2 tablespoons Asian fish sauce
2 tomatoes, cut into 1/2-inch dice
1/4 cup olive oil
1 teaspoon finely grated lime zest
3 celery ribs, thinly sliced
1 teaspoon sugar
3 tablespoons salt-packed capers—rinsed, drained and coarsely chopped
2 serrano chiles, seeded and coarsely chopped
1 small red onion, quartered and thinly sliced
2 ancho chiles, soaked in hot water for 25 minutes and drained
Fresh mint and cilantro leaves, for garnish
1 tablespoon vegetable oil
2 pounds center-cut, sushi-grade tuna steaks, cut into 1/2-inch dice
Baguette toasts or sticky rice, for serving
Remove the stem and seeds from the ancho chiles and pat dry. In a small skillet, heat the vegetable oil until shimmering. Add the anchos and fry over moderately high heat, turning once, until blistered and fragrant, about 2 minutes. Blot the anchos with paper towels and transfer them to a food processor. Let cool.
Add the serrano chiles, fish sauce, lime zest and juice and sugar to the food processor and puree until smooth. With the machine on, drizzle in the olive oil. Season with salt and transfer to a large bowl.
Add the tuna, onion, tomatoes, celery, hearts of palm and capers to the chile dressing and toss well to coat. Season with salt. Cover and refrigerate for at least 20 minutes.
Transfer the salad to a serving dish. Garnish with mint and cilantro leaves. Serve chilled, with toasts or sticky rice.