In a bowl, mix together the flour, egg, water, and salt.
Whisk vigorously until the batter is completely smooth and fluid.
Let the mixture rest for at least 30 minutes in the fridge.
Chop the ham into small pieces.
On a hot pan that has been greased, pour in a scoopful of mixture for the first crêpe.
Turn the crêpe over and crack an egg on it.
Add ½ slice of ham and a portion grated gruyère cheese on top of the crepe.
When the egg white is cooked, fold the sides of the pancakes towards the center.
Repeat as many times as necessary to use up the crêpe mixture.
Season with salt and pepper and serve.
