Whisk curds,add the salt, red chilli powder, chaat masala and mix well. Taste and adjust seasoning.
Add the potatoes, green chilli and coriander leaves. Mix well.
Transfer to a serving bowl. Garnish with roasted cumin powder. Refrigerate until required.
also for additional flavour : heat oil splutter mustard seeds red chillies and add this to the raita (purely optional)