Agnello alla piacentina is lamb cooked the Piacenza way: the meat is browned with onion, then left to cook with herbs, wine and a little tomato. That sequence is why the dish earns a place at Easter, when a slow, savoury braise feels like a feast rather than everyday fare.
Colour comes first. Onion and lamb take the heat together until they brown, then herbs, wine and a modest tomato finish the pot. The wine lifts the juices; the tomato is only a hint of sweetness and colour, not a heavy sauce. It is a kitchen method built for patience, not spectacle, and it is still spoken of as an Easter dish.
If you meet the same plate under another spelling, the Emilia-Romagna PAT listing pairs Agnello alla piacentina with Agnel äla piasinteina. That pairing is the practical clue: Italian name and dialect name belong to one entry, so a menu or market stall using either form is pointing to the same Piacenza lamb.