Peel the mangoes, cut the pulp into cubes, puree with a blender. Add the mango nectar. Peel the rhubarb, cut into small pieces, add to the mango puree, up to a total weight of 2 kg.
Stir in citric acid and preserving sugar.
Bring to the boil and boil for about 5 minutes, make a gelling test, pour hot into the prepared glasses.