In a large bowl, combine the dry ingredients: flour, corn flour, baking powder, salt, and optional sugar.
Mix in the softened butter with your hands, then add the egg and milk. Knead several times until all the ingredients have been incorporated. Then let it rest for about 30 minutes. You should have a smooth dough that easily forms a ball.
Dust your work surface with a little flour, then roll the dough out to about 1 inch thick. Cut it into about three sections with a sharp knife, then cut those sections into thin strips.
Take three strands and stretch them carefully until they're of even thickness all the way down. Pinch the ends together at one end.
Braid it by taking the left strand and crossing it over the middle strand, then take the right strand and cross it over the middle strand. When braided, tightly pinch it to seal the other end.
Heat at least 3 inches of vegetable oil in a pot until it's at least 350℉ (180℃). Test to make sure the oil is hot enough by putting a piece of dough into the oil. If it's not hot enough, the batter will stay at the bottom of the pot rather than rising to the top. If using a deep fryer, fry at 350℉ (180℃).
Gently place koeksisters in the pan, and fry for a few minutes until the bottom side is golden brown. Gently turn them over and fry for a few more minutes until the other side is golden brown.
With a large slotted spoon or something similar, remove them from the oil, let excess oil drain back into the pot, and place them directly in the syrup.
Soak in the syrup for a little while (a few minutes will do, but not so long they get soggy).
Transfer to a cooling rack to cool completely before eating.