The unique elements of South African cuisine are two-fold IMHO; first, good (rare) grilled game meats - ostrich, springbok, kudu etc., often served in imaginative berry-based sauces and, secondly, Cape Malay dishes - food influenced by the Indian and Asian origins of the communities formed of those who the Dutch brought to SA as slaves. More here:

http://www.inmamaskitchen.com/FOOD_I...eMalayart.html

Finding places that serve the former is far from difficult in Cape Town or South Africa as a whole and, yes, "high-end" places may find them too cliched and unimaginiative (as they see it) to serve, so look at mid-range places. Finding good Cape Malay is less easy. Your best bet is probably the Cellars-Hohenort at Constantia, which I can personally recommend. Link below. Avoid the Bo-Kaap Combuis (see my note above)

http://www.cellars-hohenort.com/food...ne/cape-malay/

Hope this helps.