In English salsa verde literally translates as green sauce. This can be the cause of some confusion because there are many green sauces in this world. Wikipedia cites five variations and suggests a shared history for the European versions:
The basic recipe is probably from the Near East and, as such, is probably at least 2,000 years old. Roman legionaries brought it to Italy, from where it was exported to France and Germany. Evidence suggests that it was introduced in Frankfurt am Main by the Italian trading families Bolongaro and Crevenna around 1700. A possible origin of the German variant are French Protestant immigrants emigrating to Kurhessen in the 18th century.
In this post, I am dealing with the Italian version.
That established, there is still the problem of agreeing what goes into it. All the recipes I have seen include parsley, vinegar, olive oil, anchovies, garlic and capers, but the uniformity stops there. Many recipes include additional herbs, such as mint, basil, dill, coriander, or any or all of the above. Some use breadcrumbs or stale bread as a thickening agent, while others include mustard, lemon, cornichons or gherkins, onion or shallot. The most peculiar recipe I have seen included a potato and the yolks of two hard-boiled eggs. This was stranger still because it was in The Silver Spoon, the self-proclaimed 'bible of authentic Italian cooking’. That said, the book also includes recipes for langoustine cocktail, curried chicken puffs and 10 types of soufflé, so I shall not take everything they write as gospel.
"Traditionally, ingredients were coarsely chopped by hand but now it is frequently blended into a coarse sauce using a food processor" (Wikipedia). I prefer the traditional method, but it depends what I am using the sauce for. If I am using it on pasta, crostini or in a potato salad, I would tend to use a blender for a smoother consistency. As a condiment for meat or fish, I favour a rough texture.
My preferred herbs are parsley, dill and coriander, which is because I am especially fond of salsa verde and fish, with which dill has a particular affinity. I also add a squeeze of lemon in this case. If I were planning ahead I might substitute dill for mint, for example if I were serving the sauce with lamb. However, more often than not I make this to save old herbs from the compost bin, in which case anything goes.
I have been making this for years now, but for the first few my salsa verde tended to have a bitter aftertaste when made in a food processor. I have since realised that this can be avoided by just using the leaves of the herbs or at least getting rid of the thickest stems. I also find that some extra virgin olive oils can have the same effect, so tend towards a medium-flavoured one instead, although this is not essential. If you do end up with some bitterness, an extra anchovy and/or some more capers can help to mask it.
Whenever I am making something with capers in it that calls for vinegar as well, I use the vinegar which the capers are pickled in to accentuate that flavour. If you don’t have enough vinegar in the caper jar or you’re using salted capers, replace this with white or red wine vinegar.
Makes approximately 125ml.
Put most of the parsley, dill and coriander leaves in the food processor, leaving aside a small handful. Add the anchovy, garlic, most of the capers and the vinegar. Turn the processor on and pour in the olive oil while it is running. Finally add the leftover herbs and capers and use the pulse action to roughly chop and mix them through. Season with black pepper.
Chop the herbs to the desired consistency and put in a mixing bowl; for a more dynamic consistency chop half the leaves finely and the rest roughly or not at all. Mash the anchovy with a fork, finely chop the garlic and most of the capers and add to the mix along with the vinegar. Add the olive oil a little at a time, stirring until you have the desired consistency. Season with black pepper.