Soak the onion rings in a bowl of ice cold water for 5-15 minutes. Drain the water.
In a mixing bowl, add the onion, salt, chilli powder, cumin and chaat masala, lemon juice and coriander leaves.
Toss to combine and serve immediately.
Notes
Do not slice the onion too thin, as they will wilt and become soggy quickly. Sub the coriander for mint leaves if you like.Leave out ground cumin and chaat masala if you enjoy it plain.