Rome, Lazio — abbacchio (milk-fed lamb) is specifically the Easter meat of Rome and the Lazio countryside. The tradition of slaughtering milk-fed lambs for Easter has pagan and Christian origins simultaneously — the Easter lamb symbolism and the spring lamb availability coincide.
Abbacchio (milk-fed young lamb, slaughtered before weaning — under 6 weeks old) is the defining meat of the Roman Easter table. Abbacchio alla romana is the pan-roast: joints of milk-fed lamb browned in olive oil and lard, then braised with white wine, vinegar, rosemary, garlic, sage, and anchovy until the lamb is completely tender and the pan juices have reduced to a glassy, intensely savoury sauce. The anchovy dissolves completely and seasons the sauce without announcing itself — it is the technique (also found in saltimbocca and in many Roman preparations) of using anchovy as an invisible umami amplifier.
Abbacchio alla romana is delicate and bright — the milk-fed lamb is sweeter and more tender than any older animal; the vinegar and anchovy give the sauce a complexity that straightforward braising doesn't achieve; the rosemary and sage are restrained, perfuming rather than dominating. It is Roman Easter on a plate.
Brown the abbacchio joints (leg, shoulder, or mixed) well in olive oil and lard — a deep, even brown on all surfaces. Remove. In the same fat, sauté garlic and rosemary briefly. Return the lamb. Deglaze with dry white wine (reduce by half). Add white wine vinegar (2-3 tablespoons — the acidity is characteristic of the Roman lamb preparation), sage leaves, and desalted anchovy fillets (2-3). The anchovies dissolve in the fat within 2-3 minutes of heat. Braise covered at very low heat for 45 minutes to 1 hour until the lamb is completely tender. The sauce should be reduced to a glassy, rich pan-juice.
The abbacchio's youth means it cooks much faster than mature lamb — 45 minutes is often sufficient. Test with a knife tip: if it enters without resistance, the lamb is ready. The vinegar note in the finished sauce should be perceptible but not aggressive — a pleasant, slightly sharp brightness. Serve with simple grilled or fried potatoes.
Using mature lamb instead of abbacchio — the flavour and tenderness are completely different. Skimping on the vinegar — the slight sharpness from the vinegar is the defining character of the Roman preparation, distinguishing it from all other Italian braised lamb. Not allowing the anchovy to dissolve completely — it should disappear entirely into the sauce.
Marcella Hazan, Essentials of Classic Italian Cooking; Giorgio Locatelli, Made in Italy