Peel the sweet potato and cut it in half lengthwise. Then slice it in 1/4th inch thick pcs.

Heat oil in medium pot ( it should have a tight fitting lid).

Add in the mustard seeds, wait for them to crackle.

Add in the asafetida,fenugreek seeds and then add in the sliced potatoes.

Stir to coat and then reduce heat to medium low, cover and cook until potatoes are slightly cooked.

You don't want them cooked through at this point because they will cook more along the fenugreek. You can do a simple test to check for partial doneness - If you insert a fork in the potatoes they will offer a some resistance.

At this point, add in the cayenne, salt and the fenugreek leaves. Stir gently to coat and cover and cook until the fenugreek leaves are sautéed completely and the sweet potatoes are cooked through.

For the authentic Gujarati taste, use a pinch of sugar in the end, mix and serve.