Heat 1/2 tsp olive oil in a large heavy non-stick skillet over medium heat. Add chicken, and sauté until golden and no longer pink inside. Remove from skillet; wipe skillet dry.

In same skillet, heat California walnuts over medium-high heat. Cook and stir until golden and fragrant. Remove from skillet.

Spray skillet with cooking spray. Add carrots and garlic, sauté 1-2 minutes over medium heat.

Add broth, lemon juice, green onion, and chicken to skillet; bring to a boil.

Stir in couscous; cover, remove from heat, and let stand 5 minutes. Toss couscous mixture with a fork; stir in California walnuts, salt and pepper. Serve in bowls; garnish with thin lemon slices, California walnut halves, and green onion tops.