1Pit the olives. If you’re using oil-cured olives, you can simply squeeze out the pit; with brined olives you might have to flatten the olive with the side of a knife, which will split it and allow you to remove the pit.
2Combine the olives, capers, anchovies, and garlic in a food processor or blender, along with some of the olive oil. Pulse the machine once or twice, then add the remaining olive oil a bit at a time, pulsing between additions. Do not keep the machine running; you want a coarse, chunky, uneven blend—what you’re trying to do is mimic the kind of paste you’d get with a mortar and pestle (which you can certainly use, if you feel like it; I never would).