put 1lb hulled and lightly rinsed strawberries into food processor and whiz to a purée. Add 6ozs caster sugar and whiz again. Add 1 pint of water plus 3 tablespoons of freshly-squeezed lemon juice and whiz again. Sieve through NYLON sieve (metal can discolour fruit), then transfer into plastic freezer box and freeze for about 2 hours or until the edges of the mixture are frozen but the middle is still liquid. Remove from freezer and fork the mixture over until it becomes granular. Put back into freezer for another hour, then remove, fork it over again, then serve, topped with sprigs of spearmint.