This place is just aptly named as Nasi Campur restaurant. The location is strategically located at 2nd floor opposite SPP book store and just outside the door to De Centrum Residences.
This place is popular with the working crowd and can get crowded during weekdays. The reason is probably this place offers an alternative to all the Indian Muslim (mamak) and middle eastern restaurants in DeCentrum Food is all self service, take whatever you want and order your drink.
Inside the restaurant there is a stall selling Japanese takoyaki (octopus rice balls), I didn't try it as wasn't really in the mood.