For the blood orange jelly, squeeze the blood oranges (about 2.5 kg), measure the amount so that it makes 1 liter.
Peel the tangerines and remove all white skins. Mix blood orange juice and tangerine pieces, add the jelling sugar and bring to a boil.
Boil for about 7- 9 minutes until bubbly, check for gelatinization. When the jelly test is appropriate, pour the jelly into prepared jars and seal.