Heat 1 tbsp oil in a pan or a kadai.
Fry the coriander seeds, red chillies, asafoetida, pepper and Bengal gram.
Add the coconut and fry till reddish in colour.
Allow it to cool and grind it to a paste.
Peel the small onions and chop them finely.
Heat 3 tbsp oil in a pan or a kadai and add mustard seeds and curry leaves. When mustards crackle, add the small onions and fry well for 5 mins.
Add turmeric powder and the ground masala and stir on low heat till the oil oozes out.
Add the tamarind juice with 1/2 cup water and simmer.
Add salt and allow it to boil.
Cook till the raw smell of the tamarind goes and the kolambu thickens.
:- Serve hot with rice and pappad.