Roast the eggplant on an open fire (medium flame), till all the skin is burnt and the eggplant looks soft.
Peel off the burnt skin and remove the top/stem of the eggplant.
Mash the eggplant roughly, in a mixing bowl.
Add the mustard oil, onion, tomato, green chillies, garlic, coriander leaves and salt to taste. Mix well.
Add a squeeze of lime juice and mix well.
Serve as a side dish in combination with foods like plain boiled rice and Lehsuni Daal (garlic-flavored lentils), or plain boiled rice and Rajma (red kidney bean curry).