Heat the oil in a wok or large pot to 180ºC (355°F).
Fry the eggplant, in batches, for 4–5 minutes or until golden. Remove from oil and drain on paper towel. Set aside. Reserve the oil.
To make the tamarind sauce, heat ⅓ cup (80 ml) of the reserved oil in a wok or frying pan over medium heat.
Add the onion, chilli and garlic and cook, stirring continuously, for 1 minute or until beginning to colour.
Add the curry leaves and cook for 1 minute or until wilted.
Add the sugar, tamarind, cumin and salt and simmer gently for a further 5 minutes.
Adjust seasoning, if necessary. There should be equal balance between the sweet, sour and salty flavours.
Add the fried eggplant, stir to coat thoroughly and simmer for 3 minutes.
Remove from heat, stir through the diced tomato and coriander leaves.
Scatter with fried shallot slices to serve.