Mix all the ingredients thoroughly and add the oil gradually until the mixture assumes the consistency of a proper sauce.
Taste and, only if required, add salt.
Useful tips and interesting facts
Green sauce, also known as bagnetto or bagnetto verde, is a sauce of ancient origin and yet, down through the years, the recipe has remained unchanged. It works marvellously with boiled meat as well as with ox tongue.
Since its ingredients include anchovies and capers preserved in salt, it's always advisable to taste the sauce before adding salt, to avoid the risk of overdoing it.
This recipe calls for garlic but if you prefer a lighter version, remove the inner core from the garlic clove. In this way, your green sauce will be more digestible.
For a perfect egg yolk, place the eggs in a pan of cold water. Bring to the boil and remove the eggs after 9 minutes.
A perfectly executed green sauce also depends on the parsley being dried thoroughly before it is chopped.
Try making green sauce with the addition of other chopped herbs such as basil, thyme and marjoram.
For a more modern version of Piedmontese mixed boiled meats (bollito misto), pull the meat apart and dress it with oil, salt, pepper and a sprinkling of vinegar. Toast two pieces of sliced bread and fill them with the meat and a generous dollop of green sauce. Here you have an all-Italian version of the famous and iconic Japanese sandwich, the katsu-sando.