Quarter the pears and use a teaspoon to scoop out the core. Put the quarters into a saucepan and cover with water. Add the lemon juice and a little sugar.
Bring to simmering point and gently poach the pears for about 5 minutes or until the fruit is soft - the time will depend on the ripeness of the fruit.
Leave to cool in the syrup, then puree in a food processor or with a hand-held blender. Divide into portions and serve or freeze.