Heat oil in a saucepan over medium heat, and cook the garlic for 2 minutes. If using dried basil, add now, with the water or stock, and bring to a boil. Stir in couscous, cover, and remove from heat. Let stand for 5 minutes. Fluff with a fork. Stir in tomatoes, parsley, and the fresh basil if using. Season with salt and pepper to taste.