1) Put half of the water in a large mixing bowl. If you're using a stand mixer like a Kitchenaid mixer, put it directly in the mixer bowl. Rain the teaspoon of unflavored gelatin evenly over the surface of the water and set aside.
2) Put the remaining water, sugar, corn syrup, and salt in a small saucepan and cook over medium-high heat. Don't stir it, just give it the occasional swirl, if necessary. Cook until the temperature reads 240 degrees Fahrenheit (soft ball stage) on a candy thermometer.
3) Pour the hot mixture into the bowl with the gelatin mixture. Whip on a low speed for two minutes, then add vanilla, and whip on high speed for several minutes, until the mixture is thick, white, and fluffy.
Store in jars in your fridge. You can microwave it for 10 seconds at a time to soften it and make it easy to pour or spoon onto your ice cream!