Step 1

Place cubed potatoes in a saucepan and cover with water. Cover with a lid and bring to a boil over medium-high heat. Once water is boiling, cook until potatoes are just tender, 5 to 10 minutes. Drain well and set aside.

Step 2

Heat oil in a large skillet over medium heat. Add mustard seeds and cumin seeds and heat until they start to pop. Add turmeric, coriander, cayenne pepper, and salt. Cook and stir until spices are fragrant, up to 1 minute, watching carefully so spices do not burn. Add onion and cook until softened, 2 to 3 minutes.

Step 3

Add drained potatoes to the skillet and increase heat to medium-high. Cook and stir to thoroughly coat the potatoes with the spice mixture. Taste and season with more salt, if desired. Serve immediately.