in a small grinder or chutney grinder, take 1/4 cup chopped mint leaves, 1/4 cup chopped coriander leaves and the chopped green chilies, garlic & ginger.
add 1/2 tbsp water and grind to a smooth paste.
in the bowl there will be some marinade left. add 1 cup water and mix the marinade with the water.
add water as required depending on quality of rice. you can add from 1/2 to 1 cup water. since I used organic basmati rice, i added 1 cup water.
add this water to the mushrooms. then add 1 cup thick coconut milk. stir well.
season with salt and stir. on a medium flame bring the mixture to a boil.
on sim or low flame cook the mushroom biryani till the rice grains are done.
it took me 12 minutes for the rice to cook. depending on the thickness and depth of pan, quality of rice and flame intensity, it can take 10 to 12 minutes.
once the rice grains are cooked, cover and allow to stand for 5 minutes before serving biryani. then gently fluff the rice with a fork.