Marinate the prawns in the Tom Yum paste and fish sauce, for 2-3 hours.
Saute them in sesame oil till half done.
Add coconut milk.
Bring the mixture to a boil.
Remove at once and pour into a green coconut shell and seal it with atta (wheat flour and water made into a dough).
Put it in an oven on medium heat for about 15 minutes.