Heat the oil in a large saucepan and add the cumin seeds, bay leaves, cardamom pods and peppercorns until they start to crackle. Add the onions and fry over a moderate heat until softened.
Add the potatoes and cook for 5mins. Stir in ½ the salt, then add the chicken and cook for 5-8 mins until lightly brown.
Add the ginger and garlic pastes, ground coriander, cumin, remaining salt, chilli powder and turmeric. Cook for a further 10mins, stirring constantly until the spices begin to release their aromas. Stir in the tomatoes and cook for 5mins, then pour in the stock. Bring to a boil, reduce the heat and simmer until the chicken is cook.
Taste and season if required. Serve with boiled rice and naan.