Grease a 13x9-inch pan and dust with confectioners’ sugar.
In a large mixing bowl, sprinkle gelatin over 1/2 cup cold water; let sit to bloom.
In a saucepan, combine granulated sugar, corn syrup, salt, and remaining 1/2 cup water. Heat over medium until sugar dissolves.
Increase heat and boil without stirring until mixture reaches 240°F on a candy thermometer.
With the mixer on low, slowly pour hot syrup into the gelatin mixture. Increase speed to high and beat for 10-12 minutes, until thick and fluffy.
Mix in vanilla extract. Quickly pour the mixture into the prepared pan, smoothing the top.
Sprinkle toasted coconut evenly over the top. Let stand uncovered for at least 4 hours or overnight.
Loosen edges and remove from the pan. Cut into squares and toss in additional confectioners’ sugar if desired.