Cranberry Frappe

A three-ingredient cranberry ice, thickened only by its own pectin and frozen to a coarse slush rather than a solid block. The whole thing hinges on straining and on stopping while it is still spoonable.

• A quart of cranberriesMeasured whole by volume, a quart is roughly 4 cups, about a pound. A standard 12-ounce bag holds about 3 cups, so a bag and a third.
• Cooking timeEight minutes at a simmer is enough for the skins to burst and collapse. Longer only drives off liquid and does nothing for the flavor.
• Forcing through a sieveThis is not optional straining, it is the texture of the finished dish. Push the hot pulp through a fine sieve or food mill with a stiff spatula and scrape the underside; leave the skins and seeds behind.
• Ice and saltEqual parts crushed ice and rock salt is a more aggressive freezing mixture than the 3-to-1 ratio usually given for ice cream, colder and faster. It will freeze the mixture hard if left unattended.
• Without a crank freezerPour the strained mixture into a shallow metal pan, freeze, and rake it with a fork every 30 minutes until it is uniformly granular. Roughly three hours.
• Freeze to a mushStop while the mixture holds a scrape mark but still slumps. A frappe that has set solid can be broken up in a food processor, though the texture is never quite the same.
• Sugar and acidTwo cups of sugar to a pound of berries is on the sweet side by current taste, but sugar keeps the ice soft; cutting it back much will give a harder, icier result.
• YieldAbout a quart and a half, serving six to eight as a dessert accompaniment or between courses.