Slice the tomatoes and raw mango.
Heat mustard oil in a tawa over a high flame.
Once hot, reduce the flame to medium and add the sliced mango, tomatoes, garlic, and green chilli.
Cook until they're nicely charred and the tomato skin starts to peel off easily.
Transfer the roasted ingredients to a plate and let them cool down.
Once cool enough to handle, peel off the tomato skin and discard it.
Transfer the peeled tomatoes, garlic, and green chilli to a chopper.
Scoop out the mango pulp and add it to the chopper.
Add roasted cumin powder, chaat masala powder, red chilli powder, sugar, black salt, salt and the leftover mustard oil.
Chop everything together for a few seconds until you reach your desired consistency.
Transfer the chutney to a bowl.
Add finely chopped onion and fresh coriander leaves. Mix well to combine.
Serve with paratha, roti, rice, or toast and experience the explosion of flavours!