Make the spice paste: In a small frying pan, heat 1 tablespoon of oil over a medium-high heat. When hot, add cumin seeds, chillies, coriander seeds, fennel seeds, black peppercorns and poppy seeds. Stir and fry briefly until lightly roasted. Put these into a large coffee grinder and grind to a powder. Empty into the container of an electric blender. Add garlic, ginger, tumeric and salt to the blender as well, along with 6 to 8 tablespoons of water. Process until you have a fine paste, pushing down with a rubber spatula if needed.
Heat remaining 4 tablespoons of oil in a large saucepan over a medium to high heat. When hot, add bay leaves, cardamon pods, cinnamon, fennel seeds, cloves and urad dal. Stir and fry briefly until urad dal turns red, then add curry leaves, if using. Stir once or twice and add onions. Fry onions until they are soft and lightly colored. Now add the spice paste. Continue to stir and fry for about 4 to 6 minutes, adding a little water to prevent sticking. Add the tomato and stir and fry for another 3 to 4 minutes.
Add the chicken pieces to the onion and spice mixture. Stir until they are well coated then add 2 1/2 cups water, just enough to cover. Bring to a boil. Turn the heat to low, cover and simmer until the chicken is almost cooked, about 20 to 25 minutes.
Using a slotted spoon, remove the chicken pieces. Turn the heat up to medium-high, and reduce the sauce until very thick. This should take about 6 to 8 minutes. Replace the chicken, fold gently into the sauce, and cook for a further 5 minutes before serving.