- Peel the onion, slice peeled onion into thick onion rings. make sure to use big onion. Now transfer the sliced onion ring to a mixing bowl then add ice cubes and chilled water in it. Chilled water will make the onion less bitter and extra crunchy. Let the onion rest in chilled water for 15 minutes meanwhile separate the onion rings. After 15 minutes strain the onion and add chaat masala, kashmiri red chilli powder, black salt, salt, chopped coriander leaves, lemon juice and mustard oil. It ready to serve.