Sicilian Chicken Breast with Zucchini

Squeeze juice from 1 orange (you should have 1 ⁄2 cup). Pour 1 ⁄4 cup juice and 2 Tbsp dressing into a ziptop bag. Add chicken, seal bag and marinate at room temperature 15 minutes. Meanwhile, heat outdoor grill. Remove peel and white pith from remaining 3 oranges. Cut in half and slice. Put into a medium bowl; add olives, onion, mint and remaining juice and dressing; toss to mix. Coat zucchini with nonstick spray; sprinkle with salt and pepper. Remove chicken from marinade; discard bag with marinade. Grill chicken and zucchini 8 to 10 minutes, turning once, until chicken is lightly charred and cooked through and zucchini is tender. Line individual plates or a platter with arugula; top with chicken, then orange mixture. Serve with zucchini.