Sprinkle half the curry powder over eggplant and marinate for 30 minutes.
Heat chilli oil in a large wok and fry shallots, garlic, ginger and chilli over moderately high heat until softened, about 30 seconds, then add remaining curry powder.
Add spiced eggplant and seal.
Stir in tamarind liquid, fish sauce and tomato and cook for 10 minutes