Wash and peel the mangoes.
Add water to within 1 inch of the top of the mangoes.
Boil for 30 minutes and cool.
Squeeze each pit until dry and press the pulp through a fine sieve.
Measure the pulp.
Thirty mangoes should produce about 10 cups.
Add the lemon juice and sugar and boil until thick and clear.
Pour into hot sterilized jars or glasses and seal.