Bring the water to a boil. Place the couscous in a heat-proof bowl, stir in the water, cover, and let it stand until the water is absorbed and the couscous is tender, about 5 minutes. Fluff the grains with a fork and let cool to room temperature.
In a large bowl, toss together the remaining salad ingredients. Stir in the couscous.
In a small bowl, whisk together the ingredients for the dressing. Pour it over the couscous mixture and stir to combine.