Israeli couscous has larger granules and a chewier texture than the regular variety; look for it at health-food stores, Middle Eastern shops, and many supermarkets. Serve with Shrimp in Saffron Broth from "Martha Stewart's Dinner at Home."
Heat oil in a 4-quart pot over medium-high. Add couscous; stir to coat with oil and cook, stirring, until lightly toasted, 1 to 2 minutes.
Add the water and raisins; season with salt and pepper. Bring to a boil, then reduce heat to medium-low. Cover and simmer until couscous is tender and has absorbed the liquid, 8 to 10 minutes. Remove from heat. Fluff with a fork and stir in butter before serving.