Preheat oven to 225°F. Line 2 large baking sheets with parchment paper. Place oven racks in top and lower thirds of oven.
In a medium bowl, combine sugar, cornstarch and baking powder. In a large bowl use an electric mixer on medium speed to beat egg whites and cream of tarter until the consistency of shaving foam, about 2 minutes.
Increase mixer speed to high and start gradually adding the sugar mixture, 1 Tbs. at a time over a 2 to 3 minute period. The mixture should resemble stiff glossy peaks.
Reduce mixer speed to medium and add the peppermint extract to combine. Drip 3 dots of food gel or coloring into the egg mixture at different points. Run a spoon through the food coloring 1-2 times to create streaks. (The color will continue to incorporate as you portion out the meringues.)
Using 2 spoons, dollop about 2 to 3 Tbs. of the meringue mixture onto the prepared baking sheets, leaving about 2-inches between meringues.
Bake, rotating the pans from top to bottom and front to back halfway through cooking until no longer tacky to touch 1 1/2 to 2 hours. Turn oven off and leave meringue inside to cool completely, at least 2 hours. Once cool, immediately store in an airtight container to prevent from going soft. Store at room temperature for up to 2 weeks.