Reduce the heat under the skillet to low. Add the anchovies and red pepper flakes and sauté until the anchovies have melted and the red pepper flakes are aromatic, about 1 minute. Add the tomato paste and stir until dissolved. Return the cooked garlic to the pan and stir in the tomatoes. Add the olives, capers, and oregano and allow the sauce to simmer while you cook the pasta.