Peel the garlic and deseed the chillies, then roughly chop and place into a pestle and mortar. Bash to a rough paste with a good pinch of sea salt and black pepper. Peel, finely chop and add the ginger, then bash to break it down. Peel and finely chop the onions. Drizzle a lug of oil into a large non-stick pan over a medium heat, add the cinnamon, bay and cardamom, stir for 1 minute, then add the onions. Reduce the heat slightly and fry for 15 minutes, or until softened but not coloured. Chop the chicken into 2.5cm chunks and add to the pan. Turn the heat up to medium, fry for a few minutes, then stir in the chilli paste. Cook for 2 minutes, add the remaining spices and mix well. Halve and roughly chop the tomatoes, then stir them into the pan. Bring to the boil, reduce the heat to medium and simmer for around 15 minutes, or until the tomatoes have softened and broken down. Add the yoghurt and cook for a further 10 to 15 minutes, or until the chicken is tender and the sauce has thickened and reduced. Pick, finely chop and stir in most of the coriander leaves, season to taste, then serve with a homemade naan, brown rice, a dollop of yoghurt and the remaining coriander leaves scattered on top.