Wash and soak the basmati rice in water for around 20 minutes.
For making the coconut milk, take half a cup of grated coconut in mixer jar and add half a cup of hot water and grind well.
Use a sieve or coconut milk filter to filter it and extract the coconut milk. Now put the leftover coconut back in mixer and add another half cup of hot water and grind well and sieve again. This is second extract of coconut milk and you could mix it with the first extract for this recipe. This should yield around ¾ cup of coconut milk.
Blend all the ingredients mentioned in the ground masala section to a smooth paste. You could add couple of tablespoons of water while grinding, if required.
In a kadai or handi, heat 3 tablespoons ghee and add the whole spices mentioned in the main ingredients section. Add 1 or 2 green chillies broken in half. Add diced onions and saute for couple of minutes.
Add the ground masala paste and cook for 3 to 4 minutes till the raw smell is gone.
Next add the chopped mushrooms and cook for 2-3 minutes. You could keep the mushrooms bit chunky in this recipe.
Add 1 tomato which is cut lengthwise and add turmeric powder, red chilli powder, dhaniya powder, some salt and biryani masala. Mix well and cook for couple of minutes.
Now add the soaked rice, salt to taste and some fresh mint leaves and mix gently. Cook for a minute till the rice is coated well with all the masala. Then add the coconut milk and mix.
The ratio for rice: liquid is 1:2. Since we added ¾ cup of coconut milk, so add 1¼ cup of water (for 1 cup of basmati rice). Add 1.25 cups of water and cover and cook on medium flame initially and then switch to low flame. The rice should take around 12-15 minutes to cook
Open the lid and slightly fluff up the rice using a fork to release the steam trapped in the rice. Wait for 2 to 3 minutes for the steam to escape and then gently mix. Serve with raitha.