Capetonian food appears to be either simple and fresh like the amazing fish or overly complicated and trying too hard.
Try "linefish," which is basically the catch of the day, presumably caught eco-friendly by line and hook. Typically you might encounter, Kingclip (white fleshed and flavoursome often cooked on the bone), Tuna (make sure its nice and rare in the middle) Cape Salmon (silvery fish with white, meaty flesh - tasty)Cob (meaty game fish) - crustacea is good too although I paid 25quid for a seafood platter.
Watch out for the restaurants which are obsessed with Cajun spices - its all wrong - ask for your fish to be simply cooked so you can taste the flavour.
I have eaten springbok, ostrich, Kudu and lion (actually it was Lion bar)
I can honestly say that when ostrich steak is cooked medium to rare its absolutely delicious.
If you enjoy fish and care about the sustainability of the sea then pick up the red, amber, green pocket guide from Cape Town aquarium. The small booklet tells you what is plentiful and what is overfished or endangered.
Interestingly there is a sign at the aquarium stating "No fishing!" Some people must have a cheek.
I almost neglected to mantion Biltong which is sold everywhere in Cape Town. It is basically fine slices of cured, dried beef which can be chewed. Traditionally it is made by strapping the meat under your horse thus allowing the nag to cure the meat with its sweat.