Combine the sugar, corn syrup, and hot water in a 4-quart heavy bottom kettle. Place over medium-high heat and bring to a boil. Continue to cook and bring it to a temperature of 250°F. Use a candy thermometer to check the temperature. I like using a high-quality instant-read thermometer, but a good candy thermometer fitted on your kettle will work as well.
2 cups sugar, 1 cup light corn syrup, ½ cup hot water
Once at 250°F, add in raw peanuts and unsalted butter. Raw peanuts are a must with this recipe as they have a longer cooking time at high heat. Once the peanuts are added, stir the mixture continuously so no peanuts scorch on the bottom. Bring mixture up to 310°F.
2 cups raw peanuts, 2 tbsp unsalted butter
Once at 310°F, remove from heat and add vanilla and soda. The mixture will foam and grow so make sure to stir constantly to completely incorporate.
1 tsp vanilla extract, 2 tsp baking soda
Working quickly, pour into prepared 10x15 pan. To keep the brittle light and airy, do not spread or flatten the mixture. Instead, let it flow freely.
Place in a cool area and leave until completely cooled, about 2-3 hours.
Once cooled, break into pieces as preferred.
Candy making works best when you employ mise en place (or having everything out and ready to go). This brittle process goes quickly, especially at the end and is cooked at extremely high temperatures. So having all items pre-measured and your 10x15 pan buttered and ready to go helps the process go smoothly.