First, place the water, sugar, and walnuts to a small saucepan and bring to a boil. Boil for about 2 minutes. Then remove the walnuts and place them on a dish to dry.
In a bowl, whisk the egg whites until they are foamy. Then add cornstarch and continue whisking until combined. Add the shrimp to the batter and coat each piece with a thin layer of batter.
Heat the vegetable oil to medium-high heat in a skillet or deep pan. Fry the shrimp in batches until they are golden brown, about 4 to 5 minutes.