1. Preheat oven to 450°. Place a foil-lined baking sheet in oven as it preheats.
2. Bring rice and stock to a boil in a small saucepan; cover, reduce heat to low, and simmer 25 minutes. Remove from heat; cover and let stand 5 minutes. Stir in cilantro and lime juice.
3. Place flour in a shallow dish. Place egg whites in a shallow dish. Combine panko and coconut in a shallow dish. Sprinkle chicken with pepper and salt. Dredge half of chicken in flour; dip in egg whites. Dredge in panko mixture, pressing to adhere. Place chicken on prepared baking sheet; coat chicken with cooking spray. Repeat procedure with remaining chicken. Bake at 450° for 6 minutes on each side or until done. Combine mayonnaise and remaining ingredients in a small bowl. Serve chicken with dipping sauce and rice.