Step #1 1 Whiz the blackberries in a liquidiser or food processor/blender until completely smooth.
Step #2 Sieve into a bowl to get rid of the hard pips.
Step #3 stir in the the sugar, lemon juice & 150ml/ 1/4 pint of water.
Step #4 2 Put in a plastic container & place this in the freezer for three hrs, stirring twice until the mixture is made up of large crystals but is not completely frozen.