Combine chicken broth and salt in a small saucepan; bring to a boil. Remove from heat. Add couscous; cover and let stand 5 minutes or until couscous is tender and liquid is absorbed.
Coat a small nonstick skillet with cooking spray; add oil. Place over medium-high heat until hot. Add mushrooms, celery, and green onions; saute 5 minutes or until celery is tender.
Add vegetable mixture, raisins, sunflower kernels, and lemon juice to couscous; toss gently.