Combine ¼ cup water and ½ cup sugar in a medium saucepan over medium-high heat. Stir until dissolved, about 5 minutes or so.
Cover and boil, about 3 minutes. Remove the lid and stir consistently until the mixture is a light amber color.
Keep stirring and watching the color as it turns a darker, reddish brown color. Remove from heat immediately, then stir in ¼ cup hot water. (Don’t use cold water.)
Let cool completely before using. If desired, add a pinch of salt or ½ teaspoon vanilla extract.
Store in an airtight, food-safe container such as a mason jar in the fridge for up to 1 month.
Notes
If your burnt sugar hardens and crystallizes like candy, it is not lost. You can still stir hot water into it to dissolve it back int a syrup.