Toss chicken with salt and pepper. Moisten a paper towel with cooking oil; using long-handled tongs, rub on grill rack to coat lightly. Grill chicken, covered, over medium heat or broil 4 in. from heat on each side or until no longer pink, 3-4 minutes. Cut chicken into 1-in. pieces., Divide greens among four plates; drizzle with vinaigrette. Top with chicken, mango and peas; serve immediately.