Roast calf’s liver with pancetta and persillade

My original menu at the Old Compton Wine Bar included a dish rejoicing in the name of Foie de Veau au Roy Gourmand. More simply put, this was a thickish slice of calf’s liver sautéed briefly, the pan deglazed with a little vinegar, stock and butter, then scattered with chopped parsley and garlic. The vinegar and the persillade are excellent accompaniments for calf’s liver, and to these I’ve added