Add all ingredients to a heavy bottomed, non-stick pan (see note 3).
On a medium setting, whisk the mixture continuosly until it thickens. Make sure the heat is not too high, or you may run the risk of it burning and sticking to the pan. The curd is ready when it coats the back of a spoon.
Remove from the heat and pour into a bowl. Allow to cool completely, cover and keep in the fridge. The curd will last for several days.