Candied Cranberries

A whole-berry cranberry preserve built on a fixed ratio rather than fixed quantities, which makes it easy to scale. The whole point is keeping the berries intact, so almost every instruction is about restraint.

• The hinge: do not stirThe hinge: leave it alone -- The layering — berries, then sugar as a crust, then water — looks deliberate. The recipe never mentions stirring, and the arrangement suggests the sugar is meant to dissolve down through the fruit so the syrup forms without agitation and the skins stay whole.
• The ratio in cupsHalf as much sugar as berries, half as much water as sugar. A 12 oz bag of cranberries is about 3 cups, so use 1 1/2 cups sugar and 3/4 cup water. That yields roughly 2 1/2 to 3 cups of preserve.
• "Casserole" hereRead as a deep lidded pot used on direct heat rather than a shallow baking dish, since the instruction is to cook it on the stove. Any heavy saucepan works; the weight matters because the heat must be gentle and even.
• Cook very slowlyLow heat, until the sugar has melted into a clear syrup. The recipe gives no time; go by the look of the syrup and by the berries just reaching a boil.
• Why the berries burstCranberries pop when their interiors reach roughly the boiling point and steam builds inside the skin. Covering the pot traps heat and accelerates exactly that, which is why the original allows the lid only for a moment at the very end.
• Cape Cod cranberriesA regional designation rather than a variety — Massachusetts bog fruit sold whole in autumn. Any firm fresh or frozen cranberry substitutes; frozen ones need no thawing but will throw a little more liquid.
• Setting and keepingThe syrup thickens considerably as it cools, so judge consistency cold, not hot. This is a refrigerator preserve, not a canned one; keep it covered and cold and use it within two weeks.