Roast the eggplant on a medium flame gas burner for 15-20 minutes, moving it every 4-5 minutes. It should start becoming charred and mushy and look like the picture above. I dont roast the eggplant completely like my mom does, because then the gas burner becomes very messy. The eggplant starts to drip once the skin gets charred and open. I usually put a foil and some water in the burner base to help with the cleaning later. The burner top though, you cant save:). I just char the skin to get the roasted taste in the eggplant.
Let the eggplant cool and then remove the as much skin as possible.
Mash the eggplant.
In a large pan, heat the oil.
Add in the mustard seeds and wait till they sputter.
Add in the turmeric, and coriander powder and mix well.
Add in the chopped ginger, garlic and Serrano pepper and mix well. Let cook on medium flame for 5 minutes
Add in the chopped onions and cook them till soft(5-7 minutes)
Add in the chopped tomato and the mashed eggplant and mix well.
Add in salt and cook covered on medium-low flame.
Stir every 5 minutes.
In about 10-15 minutes the mixture will start to dry up a bit.
Some people like the bharta more wet than others.. I like mine quite dry so I cook it for 10-15 minutes on low heat till it is dry and a nice earthy brown color.
Garnish with cilantro leaves and serve hot with chapatis, or Naan or any Indian Bread!