Sift the flour into a bowl. Make a well in the centre and add the eggs and melted butter. Gradually beat in the milk and water until the mixture forms a smooth batter. Strain the batter if necessary to get rid of any lumps. Cover and set aside in a cool place for 2 hours. Brush a heavy frying-pan with a little of the oil. Place over moderate heat and heat the oil until it is very hot. Remove the pan from the heat and pour about 4 tablespoons of batter into the centre of the pan. Quickly tilt the pan in all directions to spread out the batter. Return the pan to the heat and cook the crepe for just over 1 minute. Shake the pan to loosen the crepe. To see if it is cooked, lift one edge of it with a spatula; it should be light golden underneath. If it is not, cook for a further 10 seconds.

Turn the crepe over by lifting it up and over. Brown the other side for 30 seconds. This side will be less evenly browned and is the side on which fillings should be spread.

Slide the crepe on to a warmed plate and keep hot while you cook the remaining crepes in the same way.