Hull the strawberries. Place them in a bowl and sift the icing sugar over them. Mix well, and set the bowl aside, cling filmed.
Break the chocolate into small squares in a heatproof bowl, and place the bowl over simmering, hot water that is in a saucepan over a low heat. The steam from the hot water will rise, and gently melt the chocolate. The water must not boil so hard so that it directly bubbles up to touch the bottom of the bowl containing the chocolate. When the chocolate is all melted, take the saucepan and bowl off the heat, and set aside to cool gently.
Using a dry, non-stick frying pan, toast the pistachio nuts very carefully. Keep turning them, so that they do not catch and burn. When they are golden brown, and their aroma is filling the air, remove from the heat. When the nuts have cooled, chop them into small pieces. Set aside.
Whip the cream till it forms soft peaks with caster sugar. Spoon the cream into a serving bowl. Prick the bottom end of a strawberry with a cocktail stick, dip the strawberry into the melted chocolate, and then roll it into the chopped, toasted pistacchio nuts. Lay each finished strawberry on a serving platter, with the cocktail stick, so that the chocolate can reset.
Serve the strawberries with the whipped cream, for dipping into.