BLOOMING GELATIN: Pour the 1/2 cup of cold water into a stand mixer fitted with a whisk attachment. Sprinkle the gelatin evenly over the water and set aside to bloom (soften and absorb water).
STOVETOP MIXTURE: In a small heavy-bottomed saucepan, combine the sugar, corn syrup, 1/2 cup water, and salt. Stir together to moisten the sugar. Then, without stirring, bring to a boil over high heat. Insert a candy thermometer into the mixture (making sure it doesn't touch the bottom of the pot which will give an incorrect reading) and then cook the sugar syrup to 240 degrees F, (soft ball stage).
STAND MIXER: As soon as the mixture reaches 240 degrees F, remove it from the heat. Turn the mixer on high speed and slowly stream the hot sugar mixture into the softened gelatin. Make sure to slowly drizzle the syrup on the sides so it doesn't splash all around and make a mess. Once all the syrup has been drizzled in, whip on high until it is cool to the touch, about 10-15 minutes. You will watch as it goes from a milky white mixture to a very fluffy and voluminous mixture.
FLAVOR: In the last minute or so of whipping, add in the vanilla bean paste and coconut extract.
CORNSTARCH/POWDERED SUGAR: While the marshmallow mixture is whipping, sift together the cornstarch and powdered sugar in a small bowl.
PAN: Line the bottom of a 8x8-inch square baking pan with parchment paper and then rub the parchment paper with a little vegetable oil. Sprinkle a few tablespoons of the cornstarch-powdered sugar mixture evenly across the parchment.
TRANSFER: When the marshmallow mixture has thickened and cooled, scrape it into the prepared baking pan and smooth it out with a spatula dipped in water. Be prepared -- the mixture is extremely sticky! Dust the top with a few tablespoons of the cornstarch-powdered sugar mixture (don't use it all). Make sure all parts of the marshmallow cool completely, and then tightly wrap the pan with plastic wrap. Let it sit overnight at room temperature.
CUT THE MALLOWS: The next day, run a paring knife along the sides of the baking pan and invert the marshmallow onto a cutting board. Peel off the parchment and use a sharp knife (dipped in hot water and then dried off) to cut the marshmallow into cubes about 1-½ inches square (5 rows by 5). Dip the knife in hot water and dry it off before every slice for easiest slicing. Toss each cube in the remaining cornstarch-powdered sugar mixture to coat.
STORAGE: Marshmallows can be stored in an airtight container at room temperature for up to 1 month.