Heat a cooking pan or vessel and then add radish slices, onion slices, curry leaves followed by water to the level of vegetables. Let it cook in medium flame. As water starts boiling, simmer it and cook.
Meanwhile soak tamarind in half cup water for about 10 minutes. Heat a wok adding oil followed by all spices like coriander seeds, split black gram lentil, split chickpea lentil, cumin, fenugreek, red chillies and curry leaves. Roast them together till the lentils turn slightly brown. Transfer the roasted ingredients to a mixer jar and grind them along with coconut to fine paste. Add water as needed for grinding.
Next, extract tamarind juice discarding the residue. Pour this tamarind extract to radish that is cooking, add jaggery and turmeric powder too. Let it cook for few more minutes. Check if the radish slices are soft and cooked well.
At this stage include ground coconut masala from step 2. Combine everything well. Add some more water to bring the curry to the right consistency. Add salt and bring it to boil. Switch off once done.
Finally heat a seasoning pan adding oil, mustard seeds and curry leaves. As the mustard seeds splutter transfer it to radish curry.
Radish curry is ready to relish with steamed rice.