Line a medium roasting tin with foil and oil well.
Put the sugar, 150ml (¼pt) cold water, cream of tartar, golden syrup and vinegar into a large pan. Put over a low heat and cook gently until the sugar dissolves, swirling the pan occasionally. Bring to the boil for about 10 minutes until it reaches 150°C on a sugar thermometer (hard crack stage - see below for how to test).
As soon as it reaches the right temperature remove pan from the heat and cool quickly by dipping the base of the pan into cold water. Quickly stir in the bicarbonate of soda and 1 dessertspoon of cold water, swirling the pan so the mixture foams. Let it bubble for a minute then pour into the tin.
Leave to set completely then turn out and break up.
Place the chocolate in a bowl and melt in the microwave for 1-2 minutes (or place over a pan of simmering water). Dip the honeycomb into the chocolate and place on nonstick baking paper to set. Store in a tin for up to 3 days.
Hard crack test
The sugar syrup will be a rich golden brown and a little drop of caramel will be brittle when dipped into cold water.
They can be stored in an airtight container in a cool dark place for 2-3 days – after this time they will start of soften and lose their crunch.