Grind garlic, ginger, orange zest and scallion into a paste in a food processor. Add honey orange juice, soy sauce and oil and blend again.
Pour the mixture over the cubed chicken and leave to marinate for at least 1 hour, but preferably overnight.
Toss in mushrooms for the last 30 minutes to absorb the flavour.
Thread the chicken, tomatoes, pineapples, mushrooms and peppers onto 20 wooden skewers, then cook on a griddle pan or grill pan for 7 to 8 minutes on each side or until the chicken is thoroughly cooked and golden brown.
Turn the kebabs frequently and baste with the marinade from time to time until evenly cooked.