Put the water, sugar, and cream of tartar in a saucepan and bring to the boil.
Once the syrup starts to boil, add the lemon juice and continue to simmer for 10 minutes.
Cool the syrup to room temperature. Pour half of the syrup into a bowl and keep over ice to cool rapidly. Put the remaining syrup in the fridge to cool.
Dough
Sift the flour and baking powder together in a bowl and keep aside.
In the bowl of an electric mixer fitted with the paddle attachment, put the sifted flour mix, margarine, beaten ½ egg, and water.
Knead thoroughly until a smooth dough has formed.
Cover with clingfilm and leave to rest for at least 15 minutes or up to 5 hours.
Frying
Using an oiled rolling pin, roll out the dough on an oiled surface to a thickness of 5 mm – ¼ inches.
Cut the dough into rectangles of 6 x 15 cm (2 1/3 x 6 inches). Cut each rectangle lengthways into 3 strips, leaving one side uncut. Plait the 3 strips and press the cut ends together firmly.
Heat the oil to 160°C – 320°F. Fry in batches in the hot oil for 6–7 minutes, or until dark golden brown. Drain them for a few seconds on paper towels. Keep the rest of the koeksisters covered to prevent them from drying out.
Dip the koeksisters into the ice-cold syrup while they are still hot. Remove from the syrup and place on a wire rack. The syrup will gradually become hot, so when you have done about half of the koeksisters take the remaining syrup from the fridge and use this for the balance.
Recipe Notes
The colder the syrup the better! Make it the day before and place it in the fridge to ensure it is ice cold. You will get more syrup than needed, you can keep it in the fridge for more Koeksisters.