Heat oil in a pan. Add the mustard seeds and when ot splutters add the split urad dhal followed by green Chile, ginger, asafetida, and curryleaves. Saute for 20 seconds.
Add the sweet potatoes and mix. Add one third cup water, cover and cook for six minutes.
Then add the salt, mix, and continue to cook for another 6 minutes, until the sweet potatoes are crsip and tender.
Add the coconut and saute for 2 minutes. Transfer to a serving dish.
Serve warm or at room temperature with rice or flatbreads.