In a medium bowl, whisk together the cornstarch and water thoroughly. Add the coconut oil, sugar, and vanilla extract and beat until creamed.
In a small bowl, combine the all-purpose flour, baking soda, cinnamon, salt, and rolled oats. Stir.
Add the dry ingredients to the creamed mixture. Stir until just combined. Fold in the unsweetened coconut shreds.
Line a baking sheet with parchment paper, foil, or a silpat. Drop 1½ inch balls of dough onto the baking sheet 2 inches apart and press them down a little (they don't spread much). Bake for 10-12 minutes. Cool for 5 minutes on a rack before serving.