Take the yogurt in a large mixing bowl and add the following ingredients to it - salt (needed for the marinade only), turmeric powder, coriander powder, chilli powder, garam masala, ginger garlic paste, fennel seeds (1 tsp), chopped cilantro, chopped mint, cardamom (4), star anise (1), cinnamon (1 stick), bay leaf (1), cloves (3), chopped tomatoes.
Mix them up well and leave aside for at least an hour.
The more it marinates, the better it tastes.
If making the biryani for dinner, I would marinate it around lunch time.
For cooking rice:
Soak the basmati rice for about half an hour and then drain it and keep aside.
Heat about 1 tbsp of butter in a sauce pan and fry the rest of the masala items (cardamom, star anise, cloves, cinnamon, bay leaf, fennel seeds).
Add the drained rice and fry for about 5 mins in medium heat.
Add salt needed for the rice.
Add just enough water and cook the rice.
Steam the vegetables until they are just tender.
Take oil and butter in a large pan.
Add about a tsp of fennel seeds and then fry the onions.
Then add the bell pepper and fry until crisp.
Now add the rest of the cooked vegetable and salt (needed just for the vegetables) and mix well.
Now add marinade and fry until it thickens and oil separates.
Marinade would liquefy once it hits the heat but would eventually thicken as we cook it.
In a large bowl, alternate the cooked rice and the masala and mix well until combined.