For the marinade
Start by making the marinade. In a food processor, blend the ground Szechuan peppercorns, garlic, ginger, orange zest, spring onions and chilli to a rough paste.
Add the honey, soy and oils and whizz to a fairly smooth consistency. Season generously with salt and black pepper and transfer to a large bowl.
Add the chicken and coat well. Cover and marinate in the fridge for at least 4 hours, turning occasionally. Remove from the fridge 30 minutes before cooking.
Drain the chicken from the marinade and cook on the prepared barbecue grill for 7-8 minutes on each side until thoroughly cooked and lightly charred.