Basic Citrus Marmalade
2 lbs citrus fruit, such as lemons or oranges, cut into eighths
2 lbs citrus fruit, such as lemons or oranges, halved crosswise, each half cut lengthwise into quarters and sliced crosswise medium-thin
3 1/2 lbs white cane sugar
1/2 to 1 1/3 cup strained freshly squeezed lemon juice
DAY 1: Place the citrus eighths in a non-reactive saucepan where they will fit snugly in a single layer. Add enough cold water for the fruit to bob freely. In a separate non-reactive saucepan, place the sliced citrus in enough water to reach 1 inch above the tops. Cover both saucepans tightly and let rest overnight at room temperature.
DAY 2: Bring the pan with the citrus eighths to a boil over high heat, then decrease the heat to medium. Cook the fruit at a lively simmer, covered, for 4 hours, or until the fruit is very soft and the liquid has become slightly syrupy. As the fruit cooks, press down on it gently with a spoon every 30 minutes or so. The water level should stay high enough for the fruit to remain submerged as it cooks. Add a little more water if necessary. When the eighths are finished cooking, strain their juice by pouring the hot fruit and liquid into a medium strainer over a non-reactive saucepan. Cover the entire setup well with a cloth or plastic wrap and let drip overnight at room temperature. Meanwhile, prepare the citrus slices: Bring the slices to a boil over high heat, then decrease the heat to medium and cook, covered, at a lively simmer for 30-40 minutes, or longer, until the fruit is very tender. If necessary, add a little more water during the cooking; the fruit should remain submerged throughout the cooking process. When the slices have finished cooking, remove the pan from the heat, cover, and let rest overnight at room temperature.
DAY 3: Discard citrus eighths and strain the juice through a very fine mesh strainer. In a large mixing bowl, combine the sugar and cooked citrus juice. Add cooked citrus slices and their liquid. Stir well. Dip a spoon into the syrupy liquid and taste. If you do not detect a bright, tart lemon flavor, cautiously add a little bit more lemon juice, stirring and tasting as you go, until you can just taste the tartness and lemon flavor in the mixture. Transfer the mixture to a wide, non-reactive jam pan. Bring the mixture to a boil over high heat. Cook at a rapid boil until the setting point is reached; this will take a minimum of 30 minutes. Initially, the mixture will bubble gently for several minutes; then, as more moisture cooks out and its sugar concentration increases, it will begin foaming. Do not stir it at all during the initial bubbling. Once it starts to foam, stir it gently every few minutes. As it gets close to being done, stir slowly every minute or two to prevent burning, decreasing the heat a tiny bit if necessary. The marmalade is ready for testing when its color darkens slightly and its bubbles become very small. Test for doneness using the Freezer Test. The marmalade should look shiny, with tiny bubbles throughout. Once a “set” is achieved, turn off the heat and do not stir. Skim any foam from the surface. Pour the marmalade into sterilized jars and process by canning or refrigerate.