Wash mint and coriander leaves in lot of water and drain them. Dry roast cumin until aromatic and deep golden. Cool and make a fine powder in a grinder.
Add 1 tbsp of yogurt, mint, coriander, sugar, salt and chili to the same grinder jar. Grind to a smooth puree.
Whisk the rest of the yogurt until smooth. Then stir in the mint puree. Taste test and add more salt if needed. If you want you can also add lemon juice or chaat masala.
To serve with biryani or other rice dishes, I prefer to stir in chopped onions and cucumber.
Serve mint raita with any pulao, biryani, tehri or with kababs.