To make the chocolate bark base, line a baking tray that’s bigger than 10 x 25cm or a 15 x 15 tray with baking paper. Set aside.
Using a food processor, chop the freeze-dried strawberries and pistachios until they’re around crumb size and easy to scatter. Set aside.
Set up a double boiler* and add a little water to the bottom pot, enough that it covers the surface area but not too much that it touches the bottom of the heat-proof bowl siting above. Once the water is simmering – not boiling – add the chopped chocolate and let it slowly melt, stirring it frequently until it’s just fully melted, smooth and glossy. Lift the bowl out of the saucepan and away from the steam, and immediately wipe the bottom of any water droplets.
Working quickly, pour the melted chocolate into your prepared baking tray and spread it out fairly evenly with an offset spatula or back of a spoon (it doesn’t matter if there are any ridges, it just adds to the charm). Scatter the freeze-dried strawberry and pistachio crumb all over the melted chocolate slab and top with clusters of caramel popcorn.
Set the entire tray side to set at room temperature for 8 to 12 hours, or overnight.
When set, break the chocolate bark into shards and serve, or wrap in cellophane as a gift, or store in a baking-paper lined airtight container for around a week.