Bloom the gelatin by sprinkling it over 2 tablespoons of cold water in a small bowl. Let it sit for 5 minutes.
In a medium saucepan, combine the sugar, corn syrup, and 0.25 cup of water. Bring to a boil over medium heat, stirring until the sugar dissolves.
Remove from heat and stir in the bloomed gelatin until completely dissolved. Stir in vanilla extract and food coloring.
Pour the mixture into a lightly greased 8x8 inch baking pan. Let it cool completely at room temperature, then refrigerate for at least 2 hours, or until firm.
Once firm, cut into small squares and dust with powdered sugar.
Notes
Store marshmallows in an airtight container at room temperature for up to a week.