Lemon marmellata

Squeeze the juice from the lemons into a large glass or ceramic bowl. With a sharp spoon or grapefruit knife, scrape out and discard the flesh, seeds, and pith from the peels. Slice the lemon peels into narrow strips no more than 2 inches/ 5 centimeters long, and add to the bowl holding the juice. Add 4 cups/1 liter cold water to the bowl and stir gently. Cover and refrigerate overnight. Put the lemon peels and liquid into a large nonreactive pot and bring to a boil over high heat. Reduce the heat to a simmer and cook, uncovered, until the peel strips are very soft and the liquid is reduced by about half, 2 to 21⁄2 hours. Put a couple of small saucers into the freezer to chill. Then stir the sugar into the lemon peel mixture a little at a time, making sure it dissolves thoroughly. Raise the heat to medium-high and boil gently until the temperature registers 220°F/105°C on a candy thermometer, 15 to 20 minutes. Reduce the heat to medium and test to see if the marmalade has set by spooning a small amount onto a chilled saucer. Allow the marmalade to cool slightly, then tilt the saucer to one side. If the marmalade remains in place, it’s ready. If not, cook a little longer and test again. Remove the pot from the heat and allow the marmalade to cool for 10 to 15 minutes, then stir in the limoncello. Ladle the marmalade into six to eight sterilized 1-pint/500-milliliter canning jars, filling them to within 1⁄2 inch/1.25 centimeters of the rim. Wipe the rims clean, and then seal with sterilized lids and rings. Transfer the filled jars to a canning rack, submerge them in a pot of gently boiling water (make sure the jars are covered by at least 1 inch/2.5 centimeters of water), and boil for 5 minutes. Carefully lift the jars from the water with jar tongs, and place on a kitchen towel to cool undisturbed for 24 hours. Check the seal of each jar by pressing down firmly in the center of the lid; if it doesn’t move up or down, it is properly sealed. Improperly sealed jars will keep in the refrigerator for no more than 3 days. Properly sealed ones may be stored for up to 1 year in a cool, dark place.