Marinate the chicken with all the ingredients and leave in the fridge for at least 2 hours, ideally overnight.
Wash the rice and leave to soak in cold water (ideally for a minimum of two hours). Turn the oven on, and put on 50-60C heat.
Heat the vegetable oil in a wok, once it is very hot, add the onions and potatoes and cook until golden brown. (Make sure the potatoes are properly cooked through, you do not want raw potatoes in the biryani.) Leave them to drain off on a plate covered with kitchen paper.
Add the ghee or oil to a pan on medium heat, , then add the masala spices and stir. Turn the heat to low and let the spices splutter for a minute.
Then add the chicken and turn the heat to medium and cover the pan with the lid. Cook for 2-3 minutes stir, then turn the heat to low, put the pan lid back on. Cook for another 7-8 minutes, until the chicken is browned.
Then add the half of the fried onions, stir through then add the tinned tomatoes, puree and green chillies. Stir through and cover with the pan lid. Let this cook for 15-20 minutes, until the chicken is thoroughly cooked through.
Keep stirring at regular intervals to check the chicken masala is not sticking to the pan. If it is, add very small splashes of water. You don't want the masala to dry out too much, it needs to be saucy as it will cook further in the oven once combined with the rice.
Next add lemon juice, tamarind sauce and Worcester sauce. Again stir through. Then turn off the hob.
In a large saucepan, bring to boil enough water to cook the rice. Drain the soaked rice of the water and add the drained rice to the pan along with the salt and cumin seeds. Once the rice has cooked (this should take around 10 minutes), drain the water in a large sieve.
We next need to start layering the rice and the biryani masala. Add half of the rice back into the large saucepan and add two or three drops of yellow food colouring, spread gently with a fork. You don't want all the rice to be yellow, a mix of yellow and white is perfect.
Next add all the chicken masala on top of the rice. Then add some of the remaining fried onions and some of the potatoes on top of the chicken. Spread it across the pan to make a full chicken masala, onion, potato layer.
Then add the remaining rice on top of the chicken, again add 2-3 drops of yellow food colouring on the rice and spread gently with the fork. Add the remaining fried onions and fried potatoes on top of the rice.
Then cover the saucepan with a lid and put in oven for steaming "dum" for 45 minutes on a low heat, around 80C (minimum 30 minutes), this really lets everything meld together and enhances the flavours.
Then serve immediately with boondi raita and enjoy!