Salsa di prezzemolo is a parsley sauce listed among Emilia-Romagna’s traditional agri-food products, and the same entry also records it as Sälsa ad savur. That double naming already hints at a kitchen that is both official and local: a green condiment worth knowing because it sits on a regional register and still carries a dialect title.
In the Piacenza way of making it, parsley and garlic are pounded first, so the herbs break down before anything else joins them. Hard-boiled yolk then goes in, along with bread that has soaked in vinegar, oil, salt and pepper, until the mixture becomes a sauce rather than a scatter of leaves. Garlic promises aroma; vinegar-soaked bread a sharp, soaked crumb; yolk and oil the body that holds it together.
What matters for anyone following the dish further is that distinction of place and method: a PAT listing for Emilia-Romagna, and a Piacenza sequence that starts with pounding and finishes as an emulsion of yolk, bread, oil and seasoning. That is the useful frame for reading related pages on the region’s sauces—not a recipe to invent, but a clear map of what this parsley sauce is and how that one documented kitchen builds it.