Brush a 20cm (8in) square baking dish with neutral oil (or spray with nonstick spray) and line with parchment paper. Set a glass of cool water and a pastry brush next to the stovetop.
Add the sugar, honey and water to a small saucepan. Set over medium heat and, stirring constantly, completely dissolve the sugar. It is imperative that the sugar is fully dissolved ahead of the syrup coming to a boil to prevent crystallisation. Periodically remove the pan from the heat if you are concerned the mixture is heating up too quickly.
Once the sugar is completely dissolved, allow the mixture to come up to a boil and stop stirring entirely. Use the pastry brush dipped in water to wash down the sides of the pan to dissolve any sugar crystals that have collected there. Allow the sugar syrup to boil, without stirring at all, until it reaches a temperature of 150°C (300°F).
Remove the pan from the heat and immediately stir in the baking/bicarb soda and vanilla. The mixture will foam and expand as soon as the baking soda is added, do not be alarmed. Scrape the mixture into the prepared pan.
Allow the mixture to stand at room temperature until it is completely cooled and set, about 1 hour. Lift it from the pan and use a wooden spoon to break it into pieces. Serve.
Notes
I recommend using caster sugar (also known as superfine sugar) rather than granulated sugar as it does dissolve a bit quicker. However, if all you have is granulated, this is not a problem and you will still see success so long as the sugar is completely dissolved before the syrup begins to boil.
For best results, measure salt by weight, as different salts vary in crystal size and density.