There is no secret our favourite food when we go out here in Brunei is sushi. Normally we would go for sushi lunch at least two-three times a week, it's fresh, cheap, fast and so yummy! I never get tired of it.
Another favourite lunchtime hangout is our local Thai. It's a humble little place but with quite an extensive menu. Plus if you feel like something completely different that is not on the menu, they'll cook that for you too. The Thai as well has very fast service (the local McDonalds have no chance here, at all!) just like the sushi places, and is super cheap.
The other day we enjoyed quite a big lunch there, with two 'pad thai', a fried rice, some prawn tempura, a chicken curry plus some kai lan and a plate of squid - and it came to $30, for the four of us..! Reasonable, no?
Cheap and delicious food is certainly something I enjoy here in Brunei.