Combine gelatin and 1/2 cup of cold water in the bowl of an electric mixer fitted with the whisk attachment and allow to sit while you make the syrup.
Meanwhile, combine the sugar, corn syrup, salt and 1/2 cup water in a small saucepan and cook over medium heat until the sugar dissolves. Raise the heat to high and cook until the syrup reaches 240 degrees F on a candy thermometer. Remove from heat.
With the mixer on low speed, slowly pour the sugar syrup into the dissolved gelatin. Put the mixer on high speed and whip until the mixture is very thick, about 15 minutes. Add the vanilla and mix thoroughly.
To Make toasted marshmallows:
Sprinkle half the toasted coconut in an 8x12-inch non-metal pan. Pour in the marshmallow batter and smooth the top of the mixture with damp hands. sprinkle on the remaining coconut. Allow to dry uncovered at room temperature.
Remove Marshmallows from the pan and cut into squares. Roll the side of each piece carefully in confectioner's sugar. Store uncovered at room temperature.