First, cook the baingans separately. Put 2 tbsp oil in a pan and add the eggplant that had been cut into wedges. Cover the pan till it is cooked partially on a low to medium flame. Now uncover the pan , and cook it further till soft. The uncovering is done to prevent it from getting too mushy. It should stay firm.
In the meantime, bring water to a boil in a separate pan. Give 4 cuts to tomatoes and add to water. After cooking for 4 minutes, take the tomatoes out and allow them to cool down. Now put them in a blender and puree them. You may use about 5 tomatoes of medium size to get sufficient amount of puree.
Empty the pan in which you cooked the tomatoes and pour 1 tbsp oil into it. Add the garlic and let it cook for a minute. Now add all the spices: salt, turmeric, garam masala, coriander masala and red chilli powder.
Now add the fresh tomato puree and mix.
Finally, add the baingans and mix well. Cook it covered on a low flame for 5 minutes.