Choose a skillet that will hold all the ingredients.
Heat the oil over medium heat.
Add the cumin and mustard seeds. If your oil is at the right temperature you should see little bubbles forming around them. Cook for around 20 seconds.
Add the garlic ginger paste and the curry leaves. Stir until the garlic ginger paste stops sputtering.
Turn the heat down to medium low. Add the spice mix. Stir to combine the spices with the oil. You want to gently fry the spices in the oil. This is calling blooming the spices and it's where the real magic happens. Be careful though. If the spices start to stick pick the pan up off the heat. You don't want them to burn. There's no fixing burned spices.
Stir in the hotel gravy. Really mix it in to get the oil to combine. Cover and let simmer for about 5 minutes.
Mix in the coconut milk, nut paste and the tamarind paste.
Add the eggplant. Simmer for about a minute to warm through.
Look at the consistency. The nut paste really thickens this curry up. Add water until you get what you like. If you aren't vegetarian add chicken stock instead. I go for 5-6 tablespoons here.
Add the tomatoes and simmer until everything is hot.
Serve as a vegetarian centrepiece along with rice and a nice tarka dal or chana masala. Or serve it as a side to go along with your favourite curries.