In a wide pan / kadai, heat oil. Add mustard seeds. When they begin to pop, add chopped shallots / onions and chopped garlic. Fry till golden color and fragrant.
Add curry leaves and saute for 2 - 3 minutes.
Add marinated potatoes and stir well for 5 minutes on a medium heat. Cover with a lid and cook on a low heat for 10 minutes or till done and spice paste well coated on potatoes / golden color.
Serve as a side dish with Rotis / Pulao.