Preheat oven to 275°F. Line a sided baking sheet with greased foil or parchment paper. Whisk egg white and water together until foamy. Add almonds and toss to coat. Transfer to a sieve; toss gently and let drain.
Stir together wasabi powder, salt and cornstarch in a large bowl. Add almonds and toss to coat. Spread almonds on baking sheet in a single layer, and bake 30 minutes. Gently stir, reduce temperature to 200°F and continue baking 20 more minutes. Let cool completely before serving. Serve, or store airtight for up to a week.
Nutritional analysis (based on almonds): 173 calories, 6 g protein, 14 g fat, 1 g saturated fat, 9 g monounsaturated fat,
3 g polyunsaturated fat, 0 mg cholesterol, 6 g carbohydrates, 4 g fiber, 1 mg vitamin E, 238 mg sodium, 78 mg calcium