Add the water, walnuts, and sugar to a medium skillet over medium heat. Bring to a boil for 2-3 minutes.
Transfer the walnuts out of the liquid and place them on a parchment-lined plate to dry.
Whisk the cornstarch and egg whites.
Mix the shrimp into the egg mixture.
Pour about 3 inches of vegetable oil into a heavy-bottomed pot.
Heat over medium-high heat and bring the temperature up to 350 degrees.
Add up to 5 shrimp to the hot oil, frying until golden brown - about 2-3 minutes. Remove and place on a paper towel-lined plate to drain. Repeat until all of the shrimp is cooked.
Whisk the honey, mayonnaise, sweetened condensed milk, and lemon juice in a medium bowl.
Add the cooked shrimp and gently toss to coat.
Top with the candied walnuts and scallions before serving.
Notes
You can use any size of shrimp you like - just adjust the cooking time.