Peel the eggplant and dice. Put the eggplant into a medium-size saucepan with the water and turmeric. Bring to a boil, reduce heat and simmer until the eggplant is very tender. Drain and mash. Set aside.
In a different medium-sized saucepan put the oil, urad dal, mustard seeds and dried red chilies. Heat over high heat until the mustard seeds are popping and the urad dal is light brown.
Reduce heat to medium low and stir in the curry leaves, ginger paste and hing.
Add the mashed eggplant, the black eyed peas, the green serrano chilies and salt. Simmer the mixturefor 10 minutes, stirring frequently.