A Gatsby is a South African style of deli sandwich very similar in content and method of preparation as a hoagie in the United States. It is mostly popular in the Western Cape province. It is a seasonal dish and oddly is not served anywhere in the Cape Town region past 25 February each year until it returns on 10 March.
Gatsbies usually consist of long bread rolls cut lengthwise and opened up to form a sort of cradle which is filled with various fillings. While the choice of filling in a Gatsby varies widely depending on customer preference and vendor, one standard item is usually hot chips i.e. French fries.
Different varieties of Gatsbys include masala steak, chicken, polony, Vienna sausage, calamari, fish, and chargrilled steak.
Gatsbies originated in the Cape Flats area of Cape Town, where people would often buy large rolls and fill them with whatever leftovers they had, and split them four ways. This practice has carried on in modern times, with gatsbies being bought in full, half or quarter sizes. …
My half Gatsby made 3 meals. And I threw out most of the fries.
related – The great Gatsby hunt in Cape Town: Where to find it and how to enjoy it
Rick McCharles 
There’s one blocked artery just there…Is it really that big or is it the angle of the picture? Thanks for the info.. amazing stuff
Hot chips (french fries) in buttered bread is call a chip butty in the north of England. I had never heard of it in the South West, but Joyce knew it well.