Bring barley and water to a boil in a saucepan over high heat. Reduce heat to medium-low, cover, and simmer until the barley is tender, but still slightly firm in the center, about 30 minutes.
Drain and cool to room temperature in a bowl.
Puree the sun-dried tomatoes, garlic, 2 tablespoons olive oil, and balsamic vinegar in a blender until smooth.
Pour over the barley. Fold in the cilantro, olives, and remaining olive oil until blended. Cover, and refrigerate until cold. Stir before serving.
