In 1-quart saucepan, place green beans; add water to cover. Over high heat, heat to boiling. Cook 5 minutes or until tender-crisp; drain. Return beans to saucepan, cover with cold water.
Let stand 5 minutes; drain. In medium bowl, combine olive oil, lemon juice, garlic and pepper. Add chicken, mushrooms and red pepper; toss gently to coat. Cover; refrigerate until serving time, at least 2 hours.
Makes 2 cups or 2 servings.
Cajun Country -- New Iberia, Louisiana