Fraughan Preserves (Irish)

Fraughan (or frocken) is the Irish name for the bilberry - which, next to the apple, notes Theodora FitzGibbon, is "perhaps the most Irish of all fruits." A small bluish-black berry of the genus Vaccinium, the bilberry, also called the "whortleberry," is a sweet-tart relative of the American blueberry and huckleberry (either of which may be used in its place). The Irish traditionally gather bilberries (they tend to grow in bogs and sometimes under heather, and aren't always easy to find) on the last Sunday of July, known as Fraughan Sunday, and also on the ancient Celtic harvest holiday of Lughnasadh, which follows in the first few days of August. It was said that the quantity picked predicted the size of the harvest for other crops later in the season. Various medicinal properties are attributed to the bilberry, and during World War II, British aviators sometimes ate bilberry preserves before flying night missions, in the belief that it improved their night vision.

4 cups fresh bilberries, huckleberries, or blueberries, stemmed (600 g)
4 cups sugar (800 g)

Put the berries into a medium heavy-bottomed pot. Crush the berries gently but firmly with a potato masher or fork to release their juice.

Add the sugar to the berries and juice and bring the mixture to a boil over medium heat. Cook at a boil, stirring frequently to keep the fruit from sticking to the bottom of the pot, for 30-45 minutes, or until the temperature reaches 220°F/100°C on a candy thermometer. Skim any foam that rises to the surface.
Reduce the heat and test to see if the preserves have set by spooning a little onto a chilled saucer. Allow the preserves to cool slightly, then tilt the saucer to one side. If the preserves remain in a blob, they're ready.

Divide the preserves evenly between 3-4 sterilized (1 pt/475 mL jars); then seal with sterilized rings and lids.

Transfer the filled jars to a canning rack, submerge in a pot of gently boiling water (make sure the jars are covered by at least 1" (2.5 cm) of water), and boil for 5 minutes. Carefully lift the jars from the water with jar tongs and place on a dish towel to cool, undisturbed, for 24 hours.

Makes enough to fill 3-4 (1 pt/475 mL jars).