Pulse water, corn syrup and blueberries in a food processor or blender for 30 seconds. Transfer to a fine-mesh strainer and strain juice from pulp; save juice, discard pulp. Bring this juice, with the sugar, to a boil over medium-high heat in a large saucepan, stirring well. Cook, stirring frequently, until it rapidly boils for 3 minutes. Remove from heat, sprinkle the gelatin over the top and let sit for 1 minute. Whisk in the gelatin until well incorporated and dissolved; set aside and cover for 15 minutes.

In a small bowl, dissolve cornstarch in 1/2 c. cold water until smooth, making a slurry.  Whisk slurry into hot blueberry mixture and place over medium-low heat. Simmer, stirring gently, until very thick, about 4-6 minutes.

Remove syrup from heat, stir in vanilla. Sprinkle a 8x8-inch pan generously with powdered sugar. Pour the Turkish delight into the pan, and let cool in a cool, dry place (not the refrigerator) until set, 3 to 4 hours.

In the meantime, Place 1 c. powdered sugar into a large bowl. When delights are cool, cut into 1-inch squares and dredge each well with the powdered sugar in the bowl, working in batches. Don't be aftraid to really pile the sugar on.  Store at room temperature in an airtight container. When ready to serve, you may have to roll in a little more powdered sguar.

If you would like chocolate covered Turkish Delights, lightly dust each square in powdered sugar and dip in the melted chocolate. Using two forks, make sure each is well covered. Do this in batches as well. You will have to work quickly because the chocolate will harden. Place on a rack or waxed paper until chocolate shell has hardened.