In a deep-fryer or large Dutch oven, pour oil to a depth of 4-inches. Heat over medium heat until a pea-size drop of batter floats but does not swell, about 350 degrees F.
In a medium bowl, combine 2 cups of flour, 2 cups water water, and the egg. Whisk lightly until ingredients are combined (batter will be slightly lumpy). In a shallow dish, pour remaining flour. Dredge shrimp in flour and then dip into the batter. Fry in batches for 2 to 3 minutes per batch, turning to brown on all sides.
Cook's Note: When placing shrimp into oil, hold by tail and allow to fan out before starting to fry.
Remove from oil and drain on a cooling rack over a baking sheet. Serve hot with tempura sauce.
In a small saucepan, combine 2 cups water, soy sauce, sweet rice wine, and seafood stock. Bring to a boil over medium-high heat. Reduce the heat to medium-low and simmer for 10 to 15 minutes, stirring frequently.