To make traditional cranberry jelly, bring 1 cup of water and 1 cup of sugar in a saucepan to a boil, and remove from heat. Add in 12 ounces of fresh or frozen cranberries, bring to a boil, and then reduce the heat and simmer uncovered for another 10 minutes.
Pour the mash into a metal strainer placed over a bowl, and use a wooden spoon to force the pulp through. After the bowl's contents cool to room temperature, place the cranberry jelly in the fridge for up to a week before serving it.
Alternate recipes call for adding 1 strip of orange or lemon zest into the mixture as it boils for added flavor, or even swapping out some of the recipe's water in favor of orange or lemon juice. Other variations encourage reserving a small handful of whole berries to be added in before the simmer in order to increase texture.
Due to the temperature of the mix and the color of the cranberries, it's best to use glass jars or containers to prevent staining as the mixture cools. Cranberry jelly shouldn't be frozen, as the thawed jelly is often watery and loses some of its initial texture.