Grease an 18 cm × 28 cm (7 × 11 inch) rectangular slice pan. Line the base and sides with baking paper, allowing the paper to extend 2 cm – 1 inch above the edges of the pan.

Place the sugar, honey, golden syrup, and cold water in a medium saucepan over medium–low heat. Cook, stirring, for about 5 minutes or until the sugar has dissolved. Do not let the mixture boil.

Increase the heat to medium and bring the mixture to a boil. Boil without stirring until it reaches the hard crack stage on a candy thermometer (146°C to 150°C – 300°F to 310°F). Remove from the heat and let it stand for 1 minute to allow the bubbles to settle.

Working quickly and carefully, sift the bicarbonate of soda over the mixture and stir until fully combined.

Immediately pour the mixture into the prepared pan and spread it quickly with a spatula to level it. The mixture will begin to set right away.

Set the pan aside for 3 hours or until the honeycomb is firm.

Turn the honeycomb out onto a board and cut it into pieces. Serve.