Line a baking tray with parchment. Put 60ml of water, the sugar, golden syrup, butter and salt into a large pan and cook gently without stirring until the sugar melts. Turn the heat to high. Cook as the sugar first bubbles, then caramelises and eventually reaches the hard-crack stage or 154°C on a sugar thermometer

Immediately remove from the heat and mix in the coconut flakes. Quickly add the vanilla and the bicarbonate of soda and stir to incorporate them without over-mixing

Quickly tip the mixture onto the baking tray and use the back of a spoon to smooth it out thinly, not worrying about being neat or even. Leave to cool and harden

Snap into pieces or smash to a rubble in a mortar. Store the brittle in an airtight container. It will keep for a couple of months