My in-laws really enjoy citrus jellies and marmalades, but they cannot eat grapefruit because of interactions with medication. I adapted a three- citrus marmalade by replacing the grapefruits with Cara Cara oranges. I also increased the lemon a bit to compensate for the loss of tartness from grapefruit. The Cara Caras gave the marmalade a deeper colour, which is rather attractive. I'm looking forward to giving this a try with blood oranges. I got 9 half pint jars (and a bit extra for the fridge). Your mileage may vary depending on the juiciness of your oranges.
You Will Need:
3 ½ cups chopped orange pulp (use half sweet oranges and half Cara Cara)
3 ½ cups thinly sliced, seeded lemon (a mandolin slicer will help with this, otherwise use the thinnest knife you have and watch your fingers)
3 cups thinly sliced orange peel (use some of both peels)
1 ½ quarts water
Bring the pulp, lemon and peels to a boil and reduce to a simmer. Let simmer five minutes. Remove from heat, cover and let cool before placing in the fridge for 12-18 hours.
Rapidly bring the peels to a boil and cook the heck out of them. Keep in mind that the peels will not soften any more once you add the sugar so make sure you have them as soft as you like. When they reach the desired tenderness, measure the volume of the fruit and liquid. Add 1 cup of granulated sugar for each cup of fruit and liquid. Return to pot and stir until sugar is dissolved. Cook over high heat until just BEFORE the gelling point. Marmalade will get very hard upon setting and I've bent a few knives trying to pry too-hard marmalade from a jar. Remove from heat, skim foam and pour into sterilised ½ pint jars leaving ¼ inch headspace. Remove air bubbles, wipe threads clean and seal fingertip tight. Place in a boiling water canner for 10 minutes. Cool five minutes before removing. Cool 12-24 hours before checking for seals.