Dissolve the tamarind in 1/2 cup of a water. Strain it and remove the seeds and other matters.
Heat coconut oil in a pan and add mustard to it. When its done popping, add curry leaves, green chilies, ginger and a bit of salt. Suate it till it turns golden brown. Add chili powder and asfoetida powder to it.
Add the tamarind dissolved water to it, and stir continuasoly till the gravy thicken. Add salt if required.
Add the crushed jaggery and stir till it dissovles.