Heat oil in a large non-stick pan on medium-high heat.

When oil is very hot, add mustard seeds and cover the pan, allowing them to pop.

Lower heat to medium, and add curry leaves, if using.

Immediately add onion and garlic; fry until onions are translucent.

Add coriander, turmeric, cayenne, salt and stir until fragrant, about 30 seconds.

Add potatoes and stir to coat.

Cover and cook until potatoes are cooked but still firm

Stir occasionally and if potatoes are sticking to the bottom of the pan, add just a bit of water.

Uncover pan and allow the potatoes to brown slightly, occasionally stirring gently to prevent from sticking.

Serve as a side dish with a curry.