Bring a medium pot of salted water to a boil. Add the orzo and cook until al dente. Drain and rinse under running water, then drain again. Transfer the orzo to a bowl and add the olives, tomatoes, onion, parsley and capers.
In a small bowl, combine the vinegar, garlic and a pinch each of kosher salt and pepper. Whisk in the olive oil and stir the dressing into the pasta salad.