Deviled Roast Beef

A leftovers dish from the camp-cooking tradition: cold roast beef given a mustard crust and finished over the fire. The whole thing takes about five minutes once the coals are right.

• Cut the slices rightAim for about 1/4 inch thick. Anything thinner curls and dries before the crumbs colour; anything much thicker will still be cold in the middle when the outside is done.
• "Red coals" means no flameWait until the fuel has burned down to an even glow rather than a flame, so the crumb coating toasts rather than scorching. Dripping butter over open flame will flare.
• Make the crumbs stickPrepared mustard alone is a thin binder; spread it on both sides and press the crumbs in firmly. Dry crumbs from stale bread give a coarser, crisper coat than fine packaged crumbs.
• Prepared mustardMost likely a smooth, vinegary yellow or brown table mustard rather than a coarse whole-grain or a sweet honey style. A smooth Dijon is a reasonable modern stand-in.
• TimingOne to two minutes a side, only long enough to crisp the coating and heat the meat through. The beef is already cooked, and pushing it further turns cold roast grey and tough.
• Butter placementDot the butter on the upper face just before the slices go on, and again after the first turn. Butter applied at the start mostly ends up in the fire.
• Yield and servingThe recipe gives no quantities; portion by appetite. Good with a sharp pickle or watercress.