Add the vegetable oil to a medium deep skillet.
Heat the oil over medium-high heat.
In a small saucepan, combine the water, granulated sugar, and walnut halves.
Bring the mixture to a boil.
Boil for 2 minutes, stirring as needed to coat the walnuts evenly.
Transfer the walnuts to a parchment-lined baking sheet.
Spread the walnuts into an even layer and allow them to dry.
In a small bowl, whisk together the mayonnaise, honey, condensed milk, and crushed red pepper flakes.
Set the sauce aside until ready to use.
In a separate mixing bowl, combine the egg whites and cornstarch.
Beat the mixture with a handheld mixer until soft peaks form.
Working in batches, dip the peeled and deveined shrimp into the egg white and cornstarch batter.
Allow any excess batter to drip off before frying.
Carefully place the coated shrimp into the hot oil.
Fry the shrimp for 2 to 3 minutes, or until golden brown and fully cooked.
Transfer the fried shrimp to a paper towel-lined plate to drain.
Repeat the process with the remaining shrimp, working in batches to avoid overcrowding the skillet.
Place the fried shrimp in a clean mixing bowl.
Pour the prepared honey sauce over the shrimp.
Toss gently until the shrimp are evenly coated.
Transfer the coated shrimp to a serving plate.
Top with the candied walnuts.
Serve immediately for the best texture and flavor.