Irish Yellow Man Toffee

1 lb/ 1/2 kg/ 1 1/2 cups golden syrup
8oz/ 250g/ 1 cup brown sugar
1 heaped tbsp unsalted butter
2 tbsp malt vinegar
1 tbsp baking soda


1. In a large saucepan slowly melt together all the ingredients except the baking soda. Do not stir. Boil until a drop hardens in cold water (240°F, 190°C on a sugar thermometer). 


2. Stir in the baking soda. The toffee will immediately foam up as the vinegar releases the gas from the baking soda. 


3. Pour out onto a greased slab or the back of a baking tray and while just cool enough to handle fold the edges towards the centre and pull repeatedly until the whole mass is a pale yellow colour. Allow to cool and harden in a greased tin and break into chunks with a toffee hammer.