Prep Silpat. Add a silpat or silicone mat to a rimmed baking sheet. Place next to the stove.
Weigh the sugar and water. To weigh the sugar and water directly in the saucepan, add the saucepan to the food scale and turn ON. The weight should be 0. Add 200 grams of sugar, making sure it's in an even layer and not mounded in the middle. Press the on button again and tare the scale so it goes back to 0. Gently pour in 50 grams of water. The water will look like it's not enough but do not stir or shake the pan to move around the water. This will encourage crystals to form and ruin the caramel. Instead, gently set the pan aside -- the water will continue to absorb into the sugar and cover it completely.
Add corn syrup. If using corn syrup, add to the sugar and water in a thin drizzle. The corn syrup is optional but ensures an easier Dalgona-making process as it will prevent crystalization.
Weigh the baking soda. Add a small bowl to the food scale. Press the ON button and tare the scale so the weight is 0. Gently add baking soda to a fine mesh strainer until the scale shows 10 grams. Set aside.
Cook caramel. Transfer the saucepan to the stove. Cook on medium heat until light yellow in color with multiple bubbles coming to the surface.
Note: While the sugar and water cook, do not touch! Do not disturb! The entire cooking process can take anywhere from 5-11 minutes, depending on the intensity of the heat.
Add baking soda. Once the color of the sugar and water is light yellow, remove from heat. Add baking soda and using a silicone spatula, mix vigorously to fully combine, about 30-60 seconds. The caramel and baking soda together will puff up and rise dramatically. Be careful when mixing as the liquid is very hot!
Transfer to Silpat. Once the baking soda is fully incorporated and the mixture is puffy and voluminous, transfer immediately to a Silpat. Scrape every last bit onto a puffy mound in the middle, patting and shaping to to create an even layer that's 1-2 inches thick.
Cool. Cool undisturbed for 15 minutes. If the honeycomb toffee is thicker than 2 inches, it may need a longer time to cool. The candy is ready when it's cool to the touch and no longer sticky.
Crack into pieces. Using a rolling pin, tap the honeycomb toffee in several places until it cracks and smashes into different sized pieces. It's okay to create large, medium, and small pieces and not just uniformly cracked pieces.
Transfer to container. To store long term, transfer all the pieces of toffee candy to a glass container or ziplock baggie. Make sure to add all the small bits as well as the powder. Add 2 silica packets from Roasted Seaweed Snack packages (Gim) and it should stay fresh and crisp for up to 2 weeks. Do not cover until COMPLETELY COOL.