Peel the onion. Slice it into thin rings or discs using a sharp knife.
Place the onions in a mixing bowl. Separate the rings with your hands.
(optional) Soak the onion rings in water for 15 minutes to reduce the pungent taste and smell. Then discard the water.
Add red chilli powder, cumin powder, chaat masala, finely chopped green chilli, salt and lime juice. Add finely chopped cilantro/mint leaves.