Traditional is medium to coarse, with diced bits of back-fat in it.
Hog casings are used - and either pork or a pork/beef combination. It is up to you.
Main spice is Ground corriander seed - this is the essential flavour. After that, it depends on the recipe. Some people use a nutmeg/clove combination, others (like myself) use allspice (aka jamaican pepper, or pimento).
Lastly, you Boerewors includes vinegar. I use malt, some people use red-wine vinegar or apple-cider vinegar for a slightly different flavour.
Google 'boerewors recipe' or try the recipes on my website -
http://www.biltongbox.com/