The Irish Yellowman Candy is a close relative to the honeycomb toffee but unique in its own way. It's a traditional sweet treat that has been found at the Ould Lammas Fair in Northern Ireland for centuries.
Line an 8 x 8 inch cake pan with a greased parchment paper.
In a tall saucepan on a medium heat, melt the butter and then stir in the brown sugar, followed by the golden syrup. Bring to a gentle boil,stirring until the sugar has dissolved.
Turn the temperature up a bit and boil, stirring occasionally, until you reach the hard crack stage (149 °C/300 °F). Keep a close eye and the syrup will thicken and froth a lot, but you do not want it to burn.
Remove from the heat and allow to cool for a couple of minutes. Stir in the white vinegar (careful, it could spit), then quickly stir in the baking of soda. be quick and vigorous and expect the volume to triple in size.
Pour the yellow frothy toffee into the greased pan and allow to harden before breaking into pieces.