Ingredients
1 tuna steak (about 10 ounces)
Coarse salt
8 ounces chiocciole (or medium shells)
5 tablespoons extra-virgin olive oil, plus more for drizzling
Freshly ground pepper, to taste
3 tablespoons fresh lemon juice
2 small red onions, sliced 1/2 inch thick
1 garlic clove, minced
1/3 cup red-wine vinegar
2 tablespoons salt-packed capers, rinsed
1/8 teaspoon red-pepper flakes
1 head frisee, green parts only
Preparation
Bring tuna to room temperature. Meanwhile, bring a pot of salted water to a boil. Add pasta, and cook until al dente. Drain, reserving 1 cup water. Drizzle with just enough oil to coat. Spread on a baking sheet, and refrigerate 10 minutes.
Sprinkle tuna with salt, pepper, and 1 tablespoon lemon juice. Heat 2 tablespoons oil in a skillet over medium-high heat. Add tuna, and reduce heat to medium. Cook until cooked through, 5 to 6 minutes per side. Transfer to a bowl, and flake with a fork. Toss with 2 tablespoons oil and remaining lemon juice.
Heat remaining tablespoon oil in the same skillet over medium heat. Add onions, and cook until soft, about 12 minutes, adding reserved pasta water a tablespoon at a time if onions dry out. Add garlic, 1/2 teaspoon salt, and pepper, and cook for 2 minutes. Add vinegar, capers, and red-pepper flakes, and cook until the liquid has been absorbed, about 3 minutes. Add to tuna, and let cool.
Toss together pasta, tuna-onion mixture, frisee, salt, and pepper. Drizzle with oil. Serve at room temperature.
