Four distinct eggplant varieties are standard in the Thai kitchen — and no other culinary tradition uses eggplant in as many distinct forms. Each variety provides a different texture, a different bitterness level, and a different functional role in the preparations that call for it. Using the wrong variety — or substituting the large purple eggplant standard in Western kitchens — changes the character of the Thai dish in ways that cannot be compensated by technique.
Decisive moment: Adding makeua khao and makeua phiang at the correct stage in a curry — the round eggplants 10–12 minutes before service (they need time), the pea eggplants 3–5 minutes before service (they need only brief cooking before serving). If all eggplants are added at the same time: the pea eggplants are overcooked and have become soft.
David Thompson, *Thai Food* (2002); *Thai Street Food* (2010)