• 1 pound long pasta such as spaghetti
• 5 tablespoons extra-virgin olive oil
• 1 large onion, finely chopped (about 2 cups)
• 12 salt-packed anchovies, filleted, rinsed and very finely chopped, or 24 olive oil-packed fillets (about one 3-ounce jar), drained and very finely chopped
• 3 cloves garlic, finely minced
• 6 tablespoons chopped fresh flat-leaf parsley
• 1 can (6 ounces) olive oil-packed tuna, preferably Italian (see recipe introduction), drained and broken up
• 2 tablespoons capers, rinsed and chopped
• 1 to 2 cups chopped canned plum tomatoes (optional)
• Grated zest of 1 lemon (optional)
• Freshly ground black pepper to taste

Bring a large pot of salted water to a boil. Drop in the pasta, stir well, and cook until al dente.

Meanwhile, warm the olive oil in a large sauté pan over medium heat. Add the onion and sauté until tender and translucent, 5 to 6 minutes. Add the anchovies, garlic, and parsley and cook for 1 minute. Add the tuna and capers and the tomatoes and lemon zest, if using, and cook until warm, about 2 minutes.

Drain the pasta and add to the sauce in the pan. Toss well to coat, then stir for a minute or two to flavor the pasta with the sauce. Sprinkle with pepper and serve immediately.