In a mortar (or in a food processor as a second choice), pound together the parsley, garlic, pignoli, anchovies, olives, capers, and onion until uniformly combined. Gradually, pour in the oil, continuing to pound the paste until thick and sauce like. Set aside until the pasta is ready.
Cook the pasta until just al dente. Place a lightly oiled pan over medium heat. Drain the spaghetti and toss it into the pan. Cook for less than one minute, until it dries completely and just begins to brown. Place the pasta in a serving bowl and toss with the sauce and a dusting of pepper or paprika.