Soak the tamarind in boiling water, set aside for five minutes, and then strain to extract the juice. Add boiling water to the remaining pulp and extract more juice; discard the seeds and the skin.
Cooking the Daal
Soak the daal overnight or at least for 8 hours.
Rinse and Drain the water from the daal and add it into a heavy bottom pot along with fresh water, black peppercorns, baking soda and turmeric; cover and bring to a boil.
While the daal is boiling, peel and finely chop the ginger.
Once the daal has come to a boil, reduce the heat to medium and remove scum forming on the top.
Add the ginger, cover and cook for 30 minutes or until the daal is soft and breaks when pressed between your fingers.
Once the daal is cooked, add the tamarind juice and season with salt and continue cooking, covered, for another 15 minutes.
Making the Tadka
Heat the oil in a small pan. When hot, add the mustard seeds, and once the seeds start to pop, add the cumin seeds, asafoetida and chilli powder. Remove the curry leaves from the stem and add to the tempering. Please give it a good mix.