Drain the tangerines. Make up the orange and lemon juice to 400 ml with the captured juice of the mandarins. Mix the tangerines, sugar, juice and the Gelfix according to the instructions on the packet. Bring everything to a boil. Cook for about 3 minutes, skimming off the foam if necessary. Make a gelling test and fill it immediately into clean glasses. Close the jars, leave the jars upside down for about 30 minutes.
Makes 3-5 pieces, depending on the size of the glasses.