You can use other intensely flavoured fruit purées, such as strawberry or apricot, in place of the grape concentrate in this recipe.
4½ teaspoons unflavoured powdered gelatin
½ cup unsweetened Concord-grape concentrate, thawed but still cold
¼ cup cold water
¾ cup sugar
½ cup light corn syrup, divided
¼ cup water
¼ teaspoon salt
1 teaspoon pure vanilla extract
½ cup Classic Coating (plus more for dusting)
1½ cups confectioners' sugar
1 cup cornstarch or potato starch
Lightly coat an eight-by-eight-inch baking pan with cooking spray.
Whisk together the gelatin, Concordgrape concentrate and cold water in a small bowl. Let it soften for 10 minutes.
Stir together the sugar, ¼ cup of the corn syrup, water and salt in a medium saucepan. Bring the syrup to a boil over high heat and stir occasionally until it hits 250 F. Pour the remaining ¼ cup corn syrup into the bowl of an electric mixer fitted with the whisk attachment.
Microwave the gelatin on high until melted (about 30 seconds) and pour it into the corn syrup. Set the mixer to low and keep it running.
When the syrup reaches 250 F, slowly pour it into the mixer bowl. Increase the speed to medium and beat for 5 minutes. Increase to medium-high and beat for 3 more minutes. Beat on the highest setting for 1 to 2 minutes more, adding the vanilla during the last minute.
The finished marshmallow will be tripled in volume.
Pour it into the prepared pan, using an offset spatula to smooth it into the corners. Sift coating evenly and generously over top. Let set for at least 6 hours in a cool, dry place.
Use a knife to loosen the marshmallow from the edges of the pan. Invert the slab onto a coating-dusted work surface and dust it with more coating. Cut into whatever size pieces you wish (a pizza cutter works great for squares). Dip the sticky edges of the marshmallows in more coating, patting off the excess.
*To make enough Classic Coating for all three recipes below, sift 1½ cups confectioners’ sugar and 1 cup cornstarch or potato starch together in a large bowl or combine them in a food processor.