Heat the vegetable oil in a medium deep skillet over medium-high heat. Ensure the oil reaches approximately 350°F for optimal frying.

In a small saucepan, combine the water and sugar. Bring the mixture to a boil, then add the walnut halves. Let the walnuts boil for about 2 minutes until coated in a syrup-like glaze. Transfer the candied walnuts to a parchment-lined sheet and allow them to cool completely.

In a small mixing bowl, whisk together the mayonnaise, honey, condensed milk, and crushed red pepper flakes (if using). Set aside. This sauce will provide the signature creamy and sweet flavor.

In a medium bowl, whisk the egg whites until frothy. Gradually add the cornstarch while continuing to whisk until a smooth batter forms.

Dip each shrimp into the batter, ensuring it is fully coated. Fry the shrimp in batches in the preheated oil for 2-3 minutes, or until golden and crispy. Remove the shrimp from the oil and place them on a paper-lined plate to drain any excess oil.

Place the fried shrimp in a large mixing bowl. Pour the prepared sauce over the shrimp and gently toss to coat evenly. Arrange the coated shrimp on a serving plate and top with the candied walnuts.

For the best flavor and texture, serve the Honey Walnut Shrimp immediately, accompanied by your favorite side dishes such as rice or noodles.