Stuffing for Ducks

A classic English sage-and-onion stuffing with apple, sized for a pair of ducks. The instructions are complete; only the units and the sage need translating.

• Breadcrumb quantitySix ounces of finely grated stale bread is roughly 1.5 to 2 cups of dry crumbs, or a good third to half of a standard loaf gone stale. Grating stale bread on a box grater gives a finer, drier crumb than a food processor.
• The sage is the variableA scant tablespoon of finely minced fresh sage is assertive but balanced; a scant tablespoon of modern powdered dried sage would be overwhelming. Use about a teaspoon of dried ground sage, or the full tablespoon if the leaves are fresh.
• Sour cooking-appleA tart apple that collapses when cooked: Bramley if you can get it, otherwise Granny Smith. Sweet dessert apples make the stuffing cloying against rich duck.
• OnionOne fair-sized onion, chopped very fine, goes in raw. If you dislike a sharp onion edge, sweat it in the tablespoon of butter first and let it cool before mixing.
• Yield and packingThis makes something under 3 cups of mixture, enough to fill one duck generously or two lightly. Pack loosely; the crumb swells as it takes up fat and juices.
• Stuffing temperatureStuffing inside a bird must reach 165F at its center, checked with a probe in the cavity, not just at the thigh. Because duck is often roasted to render fat and served with pink breast, the stuffing can instead be baked separately in a buttered dish until set and hot through.
• The eggOne beaten egg is essentially the binder; the mixture should just hold together when pressed, not become a paste. Add it last and stop mixing as soon as it comes together.