Soak tamarind in hot water. I use a combination of new and old dark tamarind for good taste. Extract pulp and keep aside.
Heat gingelly oil in a heavy bottom pan and add hing, mustard seeds, once it splutters add fenugreek seeds and cumin seeds.
Then add the chopped garlic, vathal and fry for few seconds and then add in the small onions/shallots.
Saute the onions till it becomes translucent. Then add the chilli powder, sambhar powder and salt. Sauté for 30 seconds.
Add the tomatoes and cook till its mushy and oil separates from the sides. This may take 5-7 minutes.
Add tamarind pulp, jaggery and 1/4 cup water. Mix well and let it come to a boil.
Close the pan with a lid and cook for 3 to 4 minutes over low flame and take off stove.
Add the coconut, onions and cumin seeds to a mixer and grind to a smooth paste by adding little water.
Extract the milk from the paste and add it to the kulambu. Allow to boil for another 2-3 minutes nad turn off the flame.
Serve with hot rice and a dash of ghee or sesame oil accompanied by vadams or appalam for a hearty meal.