Couscous: In a small saucepan, bring the broth to a boil with the butter. Season with salt and pepper. Remove from the heat and add the couscous. Cover and let stand for 5 minutes. Fluff with a fork.
Chicken Stir-Fry: In a wok or large nonstick skillet, brown the onion in the oil. Add the chicken and brown over high heat. Season with salt and pepper. Add the olives and garlic and cook for 1 minute. Add the tomatoes and oregano and bring to boil. Cook for about 2 minutes or until the chicken is cook through. Adjust the seasoning.
Serve the chicken over the couscous and sprinkle with the basil.