Sprinkle the gelatin on ½ cup of cold water in a small bowl. Stir lightly with a fork. Let "bloom" for at least 5 minutes until it is very thick.
Meanwhile, heat the sugar and remaining ½ cup of water in a medium-sized saucepan until the sugar is dissolved. Then add in the gelatin mixture and mix well.
Bring the mixture to a boil. Note that the mixture will get very foamy, and the bubbles will not be stirred down.
Remove the saucepan from the heat and let sit until lukewarm.
Add vanilla, peppermint, and salt and pour into a big bowl or bowl of a stand mixer. Beat with a stand mixer, using the whisk attachment, on high speed until tripled in volume, about 8 minutes. If using a hand mixer, whisk at high speed until tripled in volume about 11 minutes.
While it is beating, prepare a 9x13 pan by lightly greasing and dusting with powdered sugar.
When the mixture has finishing whipped, pour into the prepared pan. Lightly tap the pan to remove any big bubbles from the marshmallows. Moving quickly, drop red food coloring on the marshmallows' surface and, with a toothpick, swirl it around.
Allow to set in the fridge for about 4 hours or up to overnight.
Once set, using a pizza cutter, carefully cut into even squares. Then let air dry for about 2 hours. Store in an airtight container.