Line a baking sheet with nonstick baking paper. Place the sugar in a small heavy-based saucepan over a low heat. Do not stir. Watch the sugar until the bottom layer has melted, then reduce the heat and stir until the sugar has dissolved and is a light caramel colour.
Pour on to the baking sheet, sprinkle with the sea salt and leave to harden.
When set, after about 10 minutes, use a rolling pin to break into shards.
Serve with chocolate ice cream or as a decoration for fools or syllabubs.