The Terung Dayak (Sour Brinjal, Solanum ferox L.) can be found throughout South East Asia but this plant/fruit seems to be unique to Sarawak in the sense that the fruits are used in a multitude of dishes in "Sarawak" cuisine.
I use the term "Sarawak" as it is used in cooking by nearly every community in Sarawak be they Chinese, Iban, Malay, Bidayuh or any other local races. I have not seen this fruit sold or eaten in West Malaysia or Singapore.
Easily grown locally, the plants in my garden were the result of the seeds left in the water, after washing/cutting the fruit, which I then used for watering the plants in the garden!
The ripened fruit is very sour and used in many ways to make delicious dishes and amongst my favourite dishes - in thin slices to steam with fish, quartered to cook in soup with belacan/chilli or with fish (especially terubok), and so on.
One thing about this plant - just take a look at the hook-like needle sharp thorns.
They are lethal!