Slice the banana stem finely and immerse in buttermilk till cooking time to avoid discoloration. Pressure cook rice separately and spread out on a plate to cool down.
Drain the banana stem and pressure cook in sufficient water for 2-3 whistles. Drain and squeeze out any water.
Heat oil and ghee. Temper with bay leaves, cinnamon, cardamoms, cloves, mace, star anise and cumin seeds. Saute for a few seconds.
Add the onion and fry till light brown. Then add all the dry spices (except salt) and the ginger-garlic paste mixed with 1/4 cup water. Saute till the oil separates.
Then add the tomato and continue to fry till it is mashed. Add the drained banana stem and salt. Fry for 2-3 minutes on a medium flame.
Add the rice and green chilies. Mix everything well and saute for another 2-3 minutes. Then add the mint and coriander leaves and toss well.
When done, garnish with the fried cashews and serve with raita and papad.
