Onion Tomato & Cucumber Raita

Dry roast cumin seeds and grind to a fine powder.Whisk curd so that the texture is silky smooth.Add a pinch of red chilli powder, salt and sugar and whisk.Add the finely chopped tomato, onion and cucumber.Heat 1/2 tsp oil and sprinkle pinch of mustard and cumin seeds.When they splutter,add it to the curd and mix well.Add chopped coriander and chaat masala.A pinch of black salt may be added.Serve chilled.