In a bowl toss the diced chicken with half the curry powder, garlic and a tablespoon of the tikka paste. Cover and leave to marinate for a couple of hours.
Pre-heat the BBQ and add the paella pan and a glug of rapeseed oil. Add the chicken and cook for a few minutes on a low-medium heat, until browned all over. Remove from the pan and keep warm.
Add the onion into the pan and cook on a low heat for a few minutes until softened. Add the rice and remaining curry powder and give it a good mix. Cook for 1 minute then add the stock, bring to a simmer on a medium heat.
Add the chicken back to the pan along with the rest of the tikka paste. Cook over a low heat for 12-15 minutes, stir a few times during cooking and top up with stock if it goes too dry.
Just before serving mix through a tablespoon of mango chutney and warm through some naan breads to serve with the curry.
Note: if you are using a BBQ with a dome lid you can cook with the lid on.