Walnut sauce is a delicious traditional Ligurian pesto made with, of course, walnuts. Waaait a minute, you may be saying.. pesto? Isn't 'pesto' a green sauce made with basil?
Yes, and no.
It's true that pesto is a basil sauce and also a famous Ligurian specialty. Vero also that Pesto alla Genovese, according to the L'Ordine dei Cavalieri della Confraternita del Pesto, can only, by right, be made in Genova. To prevent reinterpretations of the sauce (either made with substandard ingredients or with non-traditional additions) from being called Pesto alla Genovese, the aforementioned club (translated: Order of the Cavaliers of the Brotherhood of Pesto), green capes and all, have applied for their own DOC (Denominazione di Origine Controllata) label. This means only ingredients of approved quality originating in Liguria can be used to make Pesto labelled 'alla Genovese' and thus, protection of the name from being associated with anything other than the genuine article.
Consult any dictionary and you will invariably find that pesto means "green sauce made with basil, garlic, cheese and oil.." (apparently pinenuts are considered by purists to be an adaptation of the Savona district) but pesto can also mean 'ground or crushed'. Hence its use to explain this sauce.
The combination of the ingredients in walnut sauce is a contrast to the ingredients used in traditional pesto and does suggest some outside influence. Liguria's 350km coastline was dotted with ports, none larger than the one in Genova. Entirely conceivable that outside gastronomic combinations were also imported.. and complemented the wonderful produce of the region.
Walnut sauce is a delicious coating for fettuccine (or any sturdy long pasta) but is traditionally served with pansoti, a pocket pasta similar to ravioli but with a filling of predominantly wild Ligurian greens. These vary in composition with season ranging from swiss chard, curly endive and borage to whatever is locally available. Like the beet greens in the recipe, select ones with some backbone and flavour. Making pansoti is a little more work but worth it.
For the record, I prefer parsley (prezzemolo) in the sauce but use a little marjoram in the pansoti filling. Use nothing but the freshest walnuts. Rancid flavours, as you can imagine, will ruin this sauce. I like to gently and briefly grind a handful in a mortar and pestle or use the smash and chop technique (with the blade of a knife) to break them down to very small pieces but not make a dry paste. I also use a full fat 'farmer's' milk (4%) in place of the clotted milk or ricotta (latte cagliato). Stir it in ever so slowly and it comes together beautifully.
The Ligurian recipes here, courtesy of www.mangiareinliguria.it are perhaps some of the most authentic and unadulterated ones I have found. They are simple to prepare and taste fantastic. Their english translation is under construction..