Ingredients:

Tamarind                            : 1 lemon sized ball
Pepper corns                      : 1 tsp
Cumin seeds                      : 1/2 tsp
Garlic                                 : 3 cloves
Turmeric pdr                      : a pinch
Salt to taste
Coriander leaves               : 2tbsp( chopped)

For seasoning
Ghee or oil                        : 1 tsp
Mustard seeds                   : 1/2 tsp
Red chilli                          : 1
Curry leaves                     : few


Method:

Soak tamarind in 1 cup of warm water for 10 mins and extract the juice. Otherwise you can add tamarind as such in 2 cups of water and boil for this rasam only.
Grind or crush the pepper corns, cumin seeds and garlic together (dont grind it finely).
Take a pan, boil tamarind with salt, turmeric pdr for 5 mins. Then reduce the flame and add the crushed pepper corn cumin garlic mix.  After adding this mix just boil it till a froth comes on top of the rasam.  Remove from fire.
Heat ghee and add mustard seeds, red chilli. When it pops add curry leaves and pour it over the rasam. Add chopped coriander leaves.
You can have it with steamed rice and pappad.