Marshmallows:

Line an 8×8-inch square tin with parchment and spray with nonstick spray. Set aside.

Pour 120 milliliters (1/2 cup) red wine into a large mixing bowl (if using a hand mixer), or the bowl of a stand mixer. Sprinkle the gelatin evenly over the water. Set aside.

Combine sugar, corn syrup, remaining wine, and salt in a large, heavy-bottomed stock pot. Bring to a boil and boil, without stirring, until syrup reaches 240° F (116° C) on a candy thermometer.

Carefully pour hot syrup over gelatin. Mix on high speed until very thick and voluminous, about 8-10 minutes.

With an oiled rubber spatula, scrape marshmallow into prepared tin. Loosely cover with a well-oiled sheet of aluminum foil. Allow to set at room temperature until firm, at least 4 hours, or overnight.

Cutting and Coating:

In a small bowl, whisk potato starch and confectioner’s sugar. Coat a large chopping board with the powder. Turn marshmallow slab out onto dusted surface. Sift top with more of the powder.

With a sharp, well-oiled chef’s knife, cut into squares.

Toss cut marshmallows in additional starch-sugar mixture, coating all sides evenly.

Store in an airtight container at room temperature for up to 1 month. Do not refrigerate.