Greek Egg and Lemon Sauce

Make a roux with the butter and flour in a saucepan. Slowly add the stock over a low light stirring as you do so. Simmer for a few minutes until it has thickened. Take off the heat.

Beat the egg in a bowl along with the juice from half a lemon. Pour the sauce from the saucepan slowly into the bowl stirring all the time with a wooden spoon.

Season the sauce with salt and extra lemon juice to taste. Transfer the sauce back to the saucepan. Re-warm if necessary but do not boil or even simmer when doing this.