Soak tamarind in water and make a thick paste out of it.
Heat gingelly oil in a pan and temper with mustard seeds. Add onions and sauté until the color changes. Add chopped ginger, garlic and green chillies and sauté for few minutes.
Add chilli powder, coriander powder, turmeric powder, salt and immediately add the tamarind extract.
Give it a stir and switch off the flame when the oil separates.
Notes
1.You could also substitute ginger with mango ginger (Inji maanga) and that tastes awesome too. 2.You can refrigerate the pickle and use it for a week. If you want to store it for more days add very little jaggery while making the pickle.
Recipe by MyEdibleCravings at http://myediblecravings.com/green-chilli-pickle/