Place the tamarind pulp in a small bowl and pour the boiling water over. Let soak 30 minutes then strain out the liquid through a fine mesh sieve, pressing out as much liquid as possible.
Sprinkle the eggplant slices with salt on both sides and let drain in a colander 30 minutes. Rinse with cold water and drain.
Heat the oil in a saucepan and cook the onions, garlic and ginger until onions start browning, stirring constantly. Add curry leaves, chillies, mustard seeds, cumin seeds and ground coriander. Cook until fragrant, stirring.
Add tamarind liquid, tomato paste, water and coconut cream. Add eggplant and simmer 20 minutes or until eggplant is very soft. Garnish with coriander leaves before serving.