Grind rice and cardamom into a smooth powder.

Add the powder to the curd, whisk well, and set aside.

Heat mustard oil in a kadai.

Add cumin seeds, black cardamom, cloves, and cinnamon stick and let aroma release.

Add sliced onions and saute until softened.

Add potatoes and saute until cooked, adding water and salt if needed and covering to speed cooking.

Add turmeric powder, coriander powder, red chilli powder, and garam masala powder and saute until fragrant (3-4 minutes).

Slowly add the whisked curd mixture, keeping the heat low.

Mix well, add salt, and stir until the gravy thickens.

Cook for 2 more minutes and remove from heat.

Serve hot.