This used to be my mother's standard raita. Pacchadi can mean different things - in Hyderabad Telengana usage it can mean something uncooked - like raita (or like the uncooked tamarind pulusu in the dals and rasams list). In Andhra Telugu usage it often refers to pickle. This is a good one - really fresh and pleasing.
1 1/2 litre pot of yogurt, stirred into uniformity
1 small onion, very finely chopped
2 medium tomatoes, diced smallish
1/2 teaspoon mustard powder
1/2 teaspoon salt
1 green chilli, slit along its length
Small handful of coriander leaves (torn up small)
Small pinch of chilli powder or paprika
Put all the ingredients into a bowl, make sure the mustard and salt are well mixed in by stirring well. Leave the whole to sit for a while until the tastes of the fresh ingredients are nicely infused. Just before serving, remove the green chilli (to avoid surprises!) and garmish with a few coriander leaves and a sprinkle of chilli powder or paprika.