Method:

1. Blend together the ginger and garlic in a pestle and mortar or blender and set to one side.

2. Grind the cumin and coriander seeds and set to one side.

3. Blend the tomatoes to a paste and stir in the ground spices, garam masala, turmeric, Kashmiri chili powder, yoghurt and salt.

4. Heat the oil in a non-stick saucepan and add the mustard seeds. 

5. Once the mustard seeds pop, add the bay leaf and chopped onion.

6. Stir and cook on a medium heat. After about 15 minutes add the minced ginger and garlic with the green chilies for at least 20-30 minutes until the onions are well browned. If the onions catch, add a splash of water and continue to cook the onions.

7. Stir in the blended tomatoes, spices and yoghurt mix. Turn the heat up and stir until the mixture thickens and you are left with a thick masala paste (10-15 minutes).

8. Add the chicken pieces and stir into the thick masala to coat it. 

9. Reduce the heat and place the lid on the pan. Leave to cook for about 20 minutes, stirring every now and again.

10. The chicken will produce a lovely thick gravy. Once the chicken is cooked through you can adjust the consistency of the sauce to your preference. To loosen, just add a little hot water, or to reduce it and make it thicker, cook further on a high flame. 

11. Once cooked, add some black pepper and a squeeze of lemon, then check the seasoning.

12. Stir in the chopped coriander and serve.