To prepare the recipe, start by rinsing the fruits and using a vegetable peeler to thinly remove the zest. Cut the fruits into thin strips, removing the white membranes and partitions from the grapefruit beforehand and cutting the pulp into two to three centimeter pieces. Remove the seeds from the citrus.

Tie the thin white peels, membranes, and citrus seeds into a small bag made of cheesecloth. Cut the oranges and limes in half lengthwise, then thinly slice them. You can leave the seeds in.

Place the citrus pulp and zest, along with the cheesecloth bag, into a large pot and add six cups of warm, even hot, water. Cover the pot tightly, wrap it in a towel, and let it steep overnight. Transfer all of the ingredients for the ginger marmalade to a pot and simmer them over medium heat.

Once the mixture boils, reduce the heat slightly and continue to simmer with the lid on for 25-30 minutes, until the citrus peel is very soft. Remove the bag of seeds from the aromatic infusion with tongs or tweezers. Add the sugar to the warm fruit mixture in small portions, stirring until it completely dissolves, then bring the mixture to a boil.

Boil (stirring occasionally) until the marmalade mixture is ready to set. You can check the readiness of the marmalade mixture by scooping up a teaspoonful from the pot and dropping it onto a cold plate. When it has cooled a little, lightly press the drop with your finger. If it wrinkles slightly, the marmalade is ready for canning.

Immediately transfer the prepared marmalade directly from the heat to hot, sterilized jars, cover them with sterilized lids, and seal them. Once the jars of marmalade have cooled to room temperature, store them in a cool place (such as the bottom of a refrigerator).