Cut the aubergines into cubes and place on a baking tray. Drizzle some olive oil, sprinkle a little bit of salt and roast for about 20 minutes, mixing them halfway to make sure they don't stick to the oven tray.
While the aubergines are cooking , add some oil to a pan on medium heat and add the onion finely chopped. Stir until the onion starts to soften and then add minced or pressed garlic and ginger.
Add garam masala, coriander, turmeric and the fresh tomatoes roughly chopped.
Add water, sugar, a pinch of salt and leave simmering for 10 minutes.
Transfer to a blender jug and blend until you have a smooth sauce.
Bring the sauce back to the pan and add coconut milk and the roasted eggplant when ready.
Heat some oil in a small frying pan and add mustard seeds, curry leaves and cumin seeds. Fry until the mustard seeds start to pop.
Add the fried mustard seeds, cumin seeds and curry leaves to the curry and serve.
Notes
Serve with crushed pistachios on the top, some papadom, pickled onions and basmati rice.