How to Make It
Fill a stockpot with 6 quarts of water, cover and bring to a boil. Add 3 1/2 tablespoons salt to the water and add the linguine. Cover partially until the water just returns to a boil, then uncover, stir the pasta and cook until almost al dente. Drain, reserving some of the pasta water.
Meanwhile, in a large nonreactive skillet, heat the olive oil. Add the garlic, red pepper and fennel seeds and cook over moderate heat, stirring, until the garlic is just golden. Add the tuna and 1/2 teaspoon salt, raise the heat to high and cook until the tuna begins to sizzle; be careful not to break it up too much. Add the tomatoes and their juices and bring to a boil, then simmer over moderate heat until softened, about 4 minutes. Stir in the lemon zest.
Add the linguine to the sauce and cook over moderately low heat for 1 minute. Add a little of the pasta water, 1 tablespoon at a time, if the pasta seems dry. Serve immediately, garnished with the parsley.