In a medium bowl, combine sugar, cinnamon and pinch of salt. Set aside.
In a large bowl, whisk together egg white, vanilla extract and a-tablespoon water for about 1 minute. Add the walnuts, pecans and cashew. Stir well with a rubber spatula, making sure they are all moistened.
Stir in the sugar mixture until evenly coated.
Preheat oven to 300 degrees F. Line a baking sheet with parchment paper. Using a clean spoon, spread the nut mixture on the baking sheet in a single layer.
Bake for 20-25 minutes, stirring at halftime. Remove from the oven and cool to room temperature.