Dipping Sauce: In small bowl, stir together vinegar, water, ginger, sugar, hot pepper and salt until sugar is dissolved. Set aside.
On cutting board, cover shrimp with plastic wrap and, using bottom of saucepan, smash until flattened and broken up; transfer to bowl. Add water chestnuts, onion, cilantro, ginger, salt and pepper; mix well.
Lay 1 spring roll wrapper on work surface with point up; shape 2 tbsp shrimp mixture into 3-inch (8 cm)long log across bottom third of wrapper. Roll up, folding in sides, until only 1-inch (2.5 cm) triangle of wrapper remains. Lightly coat triangle with egg; roll up. Repeat with remaining filling and wrappers. (Make-ahead: Refrigerate for up to 2 hours.).
In heavy-bottomed skillet, heat 1/2 inch (1 cm) oil over medium-high heat just until ripples appear; reduce heat to medium. Skimming oil between batches, fry spring rolls, turning and increasing heat if necessary, until golden and filling is pink in centre, 3 to 4 minutes per batch. Drain on paper towel–lined plate. Serve with Dipping Sauce.