Heat oil in a nonstick skillet over medium-high heat. Add onion and bell pepper; sauté 7 minutes.
While vegetables cook, bring broth to a boil in a medium saucepan; gradually stir in couscous. Remove from heat; cover and let stand 5 minutes. Fluff with a fork. Stir in onion mixture, salt, and black pepper. Sprinkle with nuts.