-
1
Pat the lamb pieces thoroughly dry. Heat the olive oil in a wide, heavy-based pan over high heat. Working in batches — never crowding the pan — brown the lamb pieces on all sides until a deep golden crust forms on the pale flesh. Transfer each batch to a plate and reserve. The colour built here is the backbone of the finished dish; milk-fed lamb is almost white and will accept deep browning dramatically and quickly.
-
2
Reduce the heat to medium. Add the garlic and rosemary to the fat remaining in the pan. Cook, stirring, until the garlic is golden at the edges and the rosemary is fragrant — the oil should smell decisively of both.
-
3
Add the anchovy fillets to the pan. Stir continuously over medium heat until the fillets dissolve entirely into the oil, leaving no visible trace. This step is where the dish lives or dies: the anchovy must disappear completely, providing invisible umami depth without any suggestion of fishiness; if the fillets are merely softened rather than dissolved, that depth will not permeate the braising liquid.
-
4
Pour in the white wine and raise the heat. Scrape up any residue from the base of the pan. Allow the wine to reduce by roughly half — the sharp alcohol smell should give way to a rounder, more integrated aroma.
-
5
Return the browned lamb and any resting juices to the pan. Add the white wine vinegar. Stir to coat. Cover tightly and braise over low heat for 30–40 minutes, no longer than 45 minutes in total. The lamb is done when the pieces yield to gentle pressure with a spoon and the flesh is fully tender but holds its shape; it must not be allowed to collapse into mush.
-
6
Remove the lid and raise the heat briefly to concentrate the pan juices if they appear thin. The finished sauce should be glossy, fragrant with rosemary, and perceptibly reduced. Taste: the anchovy's presence should register only as depth and savour, never as a distinct flavour. Serve immediately, with Roman bread alongside.