1. Preheat grill to high heat.
2. Combine first 7 ingredients in a small bowl, stirring with a whisk. Place chicken in a large zip-top plastic bag. Add juice mixture; seal bag. Turn bag to completely coat chicken. Refrigerate 20 minutes.
3. Remove chicken from bag; discard marinade. Place chicken on grill rack coated with cooking spray. Place salt slab on top of chicken; grill 5 minutes on each side or until chicken is done. Serve with lemon wedges, if desired.