Hi Madeira,
You could try the following:
La Tortilla Assesina in Castle St - yummy tapas, inexpensive, nice atmosphere;
Lanna Thai in Queensgate - have not yet been there myself but friends say it is great;
Jeera - Indian restaurant Gordon Ramsay once raved about, although personally I was not impressed with the take away we got from there last week;
The Mustard Seed - Fraser St - again have not tried it myself but I hear it is very good.
There are also a bunch of places down by the river that look good so you might want to stroll along there and check them out.