Combine sugar, soy sauce, mandarin juice, garlic, ginger and sesame oil in a large bowl. Add chicken and stir to coat. Marinate for 15 minutes.
Heat peanut oil in a large frying pan over medium-high heat. Add chicken to pan, reserving marinade, and cook for 5 minutes each side or until golden. Transfer to a plate.
Drain any fat from pan. Add reserved marinade to pan, return to the heat and bring to the boil. Return chicken and cook for 5 minutes or until cooked through. Top chicken with mandarin peel and spring onion. Serve with steamed rice.