Firstly, wash the outside of the blood oranges thoroughly until they are clean of dust and other particles.
Now, cut the top and tail of the oranges and then slice them in two halves. Remove the core of each orange so that you are now rid of the seeds. Keep this aside.
Next, you thinly slice the oranges widthwise first and then lengthwise.
Take the sliced oranges and put them in a bowl filled with water. On the other hand, collect all the cores and seeds in a small cheesecloth and tie it tightly from both ends. Now, submerge this bundle in the same bowl with your blood orange slices and water. Refrigerate overnight.
In the morning the next day, remove the cheesecloth bundle and dump it. Take a large pot and transfer your blood oranges and water into it. Add sugar and stir till it mixes well. Now let the mixture boil over medium heat. Once boiled, keep it on low flame till the water reduces to its half. Keep stirring occasionally.
Your marmalade is almost ready now. Turn the heat off and place it in the fridge for ten minutes, post which it should not be too runny. If it is indeed still runny, then you may want to heat it for another 10 minutes and repeat the process till the desired consistency is achieved.
Transfer your hot blood orange marmalade to jars and store it in the refrigerator to dig in anytime.
Some people also prefer to add strawberries and wine to their marmalade. Be sure to get the measurements of each ingredient right in order to get the best results.