Asian Herbs & Vegetables by Penny Woodward is a book I find very useful, with descriptions, cultivation & uses of some of the more unusual herbs & vegtables such as Taro, Luffa, Tree Spinach. Its written from the point of view of growing them in Australia. It was published in 2000 so should be easy to find cheaply second had or on line.
The Moreton Region Library has a copy which I've reserved.
Another great book on this subject that I refer to often is "Oriental Vegetables: The Complete Guide for the Gardening Cook" by Joy Larkcom. It is an international publication, so not designed for Aussie conditions alone, but the advice on growing, pests and diseases, etc, is universal and all the unusual varieties are included with a variety of different approaches to growing and cooking. I'll never part with my copy.