Bring a large pot of salted water to a boil. When the water boils, add the linguine and cook just until al dente. Drain well.
Combine the tomatoes, onions, capers, olives, anchovies, and the coarsely chopped parsley in a medium bowl. Dress with the lemon juice and a healthy drizzle of extra-virgin olive oil, enough to lightly coat the salad (1 to 2 tablespoons). Sprinkle in the basil and salt and pepper, toss again and adjust the seasoning.
Preheat a large, deep skillet over medium heat. To the hot pan, add the 1/4 cup of extra-virgin olive oil (4 times around the pan), and half the chopped garlic cloves. When the garlic speaks by sizzling in the oil, add the bread crumbs. Stir the bread crumbs until they are deeply golden in color. Add the finely chopped parsley and a liberal amount of salt and coarse black pepper. Transfer the bead crumbs to a dish and reserve.
Return the same skillet to the heat and add the 3 tablespoons of extra-virgin olive oil, 3 times around the pan. Add the remaining garlic, the sardines, and red pepper flakes to the pan and saute over medium heat for 2 or 3 minutes. Add the hot, cooked pasta to the skillet and toss with the sardines. Add the bread crumbs to the pot and toss thoroughly to combine and evenly distribute the mixture. Taste to adjust seasonings and serve with the Puttanesca Salad alongside.