Sweet Potato Fry

1/2 teaspoon mustard seeds
1/4 teaspoon cumin seeds
1/3 teaspoon urad dal
10 curry leaves
1 tablespoon oil
1/4 teaspoon turmeric powder
3 sweet potatoes, peeled and chopped into 1/2" cubes
1 teaspoon sambar powder (or substitute 1/4 teaspoon chili powder, 1/4 teaspoon cumin powder, 1/2 teaspoon coriander powder)

Heat the oil in a shallow pan, add the mustard, cumin, urad dal and curry leaves.  When the mustard seeds pop and the urad turns golden brown, add the turmeric, then the sweet potatoes,  Stir fry for several minutes over high heat, then cover and turn heat to low.  Allow to steam-cook for about 10 minutes, stirring occasionally.  The potato should be slightly firm at this point.  (Fork tender.)  Add the sambar powder, stir fry for another couple minutes until potato is well coated. Switch off heat and leave it covered until ready to eat - the steam from the potato as it cools will finish cooking the potato.