Place the onions and okra in a bowl. Add gram flour, chili powder and turmeric and mix.
Heat oil and deep-fry a handful of okra and onion mixture until brown and crispy. Do not fry too many at a time. Remove and drain on kitchen paper towel. Toss with mango powder, chaat masala and salt.
Add lime juice and serve immediately garnished with chopped coriander leaves.