1) Preheat oil in deep-fryer to 190C/Gas 5.
2) In a large bowl, add the flour, cornflour, baking powder, sugar and salt, and mix to combine. Whisk in the soda water and mix until a batter is formed.
3) Dip the beans in the batter being sure to shake off the excess. Fry the beans in batches for 2 to 3 minutes until crispy and golden. Remove to a paper towel-lined sheet tray to drain.
Arrange the beans on a platter and serve with warm cranberry sauce.
Cook's Note: When frying the beans, make sure the fryer basket is submerged into the oil. Drop string beans into the basket in the oil to ensure the beans do not stick to the basket when cooking.