1.Place chicken in large resealable plastic bag. Add ¼ cup of the marinade; turn to coat well. Place asparagus in a second resealable plastic bag. Add remaining ¼ marinade; turn to coat. Refrigerate chicken and asparagus 30 minutes.
2.Remove chicken and asparagus from marinade. Discard chicken marinade; reserve asparagus marinade.
3.Grill chicken over medium heat 6 to 7 minutes per side or until cooked through. Grill asparagus 4 minutes or until tender-crisp, turning occasionally. Brush chicken and asparagus with reserved marinade. If desired, grill lemon slices 30 seconds per side. Serve chicken with asparagus. Garnish with lemon slices.