Curd (thick plain "natural" yogurt)
Cold water
Salt to taste
Oil
Mustard seeds
Curry leaves
Whip the curd in a bowl until it becomes soft and loosened.
Mix in half as much cold water as curd, along with salt to taste.
Heat a small amount of oil in a pan, and add mustard seeds. When hot, add curry leaves. Heat through for a few more seconds.
Mix the mustard and curry leaf into the curd mixture.
Chill the mixture well, and serve cold.