Pat the shrimp dry using paper towels.

In a small bowl, beat the egg. Place cornstarch in a separate shallow bowl.

Dip each shrimp into the cornstarch, shaking off any excess. Then, dip it into the egg before coating it in cornstarch again. Set aside and repeat with the remaining shrimp.

Preheat the air fryer to 400°F and lightly coat the bottom of the basket with oil.

Arrange the shrimp in a single layer without overcrowding. Cook in batches if necessary. Lightly brush the shrimp with oil and cook for 5 minutes. Flip and cook for another 3 to 4 minutes, until crispy and fully cooked.

In a bowl, whisk together the mayonnaise, rice vinegar, and honey until smooth. Set aside.

In a small skillet over medium heat, combine the water and brown sugar. Once simmering, add the walnuts. Reduce the heat and stir continuously until the syrup thickens and coats the walnuts. Transfer the walnuts to a parchment-lined plate to cool and prevent sticking.

Toss the cooked shrimp with the sauce and caramelized walnuts until evenly coated.

Garnish with sliced green onion, if desired. Serve immediately and enjoy!