Combine Sugar, Cinnamon, Salt and Cayenne Pepper (optional) in smaller Mixing Bowl.
Separate Egg White into larger mixing bowl. Add Water and Vanilla Extract (optional). Whisk until frothy.
Add Pecan Halves to the Egg White mixture and thoroughly coat.
Add coated Pecan Halves to the Sugar mixture. (NOTE: Remove the excess Egg White mixture by adding the Pecan Halves individually with a fork, straining off the extra egg white mixture.) Mix to thoroughly coat with Sugar mixture.
Transfer the coated Pecans to the Baking Sheet with Silicone Baking Mat (or Parchment Paper). Spread out with the Silicone Spatula, keeping Pecans in Single layer.
Bake in 225°F oven for about 1 hour our until completely dried. Check and stir every 15 minutes until about the 45-minute mark. Then start checking and stirring every 5 minutes.