Heat oil in a pan and fry the brinjal pieces on a low flame (without adding water and with the pan covered) until they are browned and cooked.
Remove from the pan, drain and set aside.
In the same oil, lightly fry the capsicum for 2 - 3 minutes. Remove from the pan , drain and set aside.
In the same oil add the cubed onions and whole green chillies and sauté till the onions turn soft and translucent. Remove from the pan, drain and set aside.