This vegetable is like a harder large pea and has a very similar flavour. It is used in dishes such as 'Gak Khiewwan Kai' (Green mince curry) to add green colour and an interesting texture to the dish.
You can buy it from asian grocers, and it can be frozen just like peas and kept for months at a time. If you cannot obtain this aubergine, use large uncooked peas, however you should add the peas later in the cooking process as peas take less to cook than these aubergines.
The aubergines also add more bite to the dish than pees.