Soak tamarind in a cup of warm water and extract the pulp.
Heat oil in a sauce pan, add mustard seeds and when they crack, add the chopped garlic, curry leaves and red chillies fry for few minutes.
Then add the chopped tomatoes, cook till it turns soft. Then add asafoetida, turmeric powder, coriander powder, chilli powder, pepper and cumin powder mix well, add some water (about 1/4 cup) and cook with drumsticks until drumsticks are tender.
Now add the tamarind extract and required water to get the right consistency, salt to taste, mix well.
Let it cook for few minutes in medium heat with two table spoon of rasam powder.
Take out the pulp from the drumsticks and add to rasam.
Garnish with tamarind and olive bread stick and serve.