Heat the oil in a skillet over medium heat, and then sauté the onion until it’s wilted and starting to brown, about 6-8 minutes. Add the garlic, chopped olives, capers, anchovy, pepper flakes and oregano, stirring for another 1-2 minutes. Add the tomatoes broken up with a fork, grind the pepper into the sauce and bring to a boil briefly. Turn the heat down so the sauce just simmers gently for about 30 minutes. While the sauce is simmering, bring a large pot of water to a boil, add a pinch of salt, and cook the spaghetti according to the package directions. Add the cooked spaghetti to the sauce pan and mix well under low heat, adding a few dollops of the pasta water to make the sauce silkier. Add grated parmesan and garnish with the minced parsley before serving piping hot.