Half-ripe fruits may be used to help the jelly set. Break the shells, scoop out the pulp with a spoon and weigh it. Allow 500 ml (1 pint) water to each 500 g (1 lb) pulp. Put fruit and water into a heavy pan and bring to the boil, then simmer until liquid is reduced to half its volume. Strain through a jelly bag or cheesecloth. Do not squeeze the bag or the jelly will not be perfectly clear. Measure the liquid and allow 3/4 cup sugar to each cup of liquid. In a clean pan cook the sugar and juice, stirring, until the jelly sheets as it falls from the spoon. It should set when a little is dropped on a cold plate. Pour into hot sterile jars and seal.
Recipe excerpted from Encyclopedia of Asian Food by Charmaine Solomon (Periplus Editions, 1998)