Step 1

Heat pasta water: Bring a large pot of salted water to a boil (1 Tbsp of salt for every 2 quarts of water). While the water is heating, start making the sauce.

Step 2

Cook onions, anchovies, garlic: Heat the olive oil over medium heat in a large, deep sauté pan. When the oil is hot, cook the onions until they're soft and translucent, about 4-5 minutes.While the onions are cooking, stir in the chopped anchovies along with some of the oil from the can.Add the finely chopped garlic and cook another minute.

Step 3

Make the sauce: Mix in the tomato paste and cook it for 2 minutes, stirring occasionally.Add the crushed tomatoes, oregano, chili pepper flakes, olives, and capers. Bring the sauce to a simmer, then lower the heat to low to maintain a gentle simmer, 10 to 15 minutes.

Step 4

Cook the spaghetti: When the salted pasta water is at a rolling boil, add the pasta. Cook the pasta according to the package instructions, to al dente, cooked but still slightly firm.

Step 5

Finish the sauce: Stir the parsley into the pasta sauce. Add some pasta water into the sauce to thin it if it has become too thick.

Step 6

Serve: Drain the pasta and put in a large bowl. If you want, mix a little olive oil into the pasta so the pasta doesn't stick together.Add a ladle's worth of sauce to the pasta and mix to combine. Serve in shallow bowls with more sauce on top.