First make the spice paste. Crush the black pepper corns in a pestle and mortar then put all the ingredients for the spice paste in a blender and blitz until you get a smooth paste. Any paste you don't use can be stored in the fridge for about a week.
Cook the onion in a saucepan for about 10 minutes then add the spice paste and cook for another 3 minutes, stirring. Then add the tomatoes and salt, cover and leave to cook over a low heat for another 8 minutes.
Remove the lid and continue to cook for about 5 minutes. Add the chicken and about 200ml of boiling water from the kettle. Put the lid on and let it simmer for about 20 minutes.
Remove the lid and let the sauce reduce little.
Serve with Indian bread or rice.
Nutritional information is approximate and a guideline only.