How to Make It
In a small saucepan of boiling water, cook the noodles until al dente, 4 to 5 minutes. Drain and transfer to a bowl of ice water to cool. Drain the noodles well and chop into 3-inch pieces.
Transfer the noodles to a large bowl and add all of the remaining ingredients except the spring roll wrappers, vegetable oil, beaten egg and dipping condiments; mix well.
In a large enameled cast-iron casserole, heat 2 inches of oil to 350°. Arrange 1 wrapper on a work surface with a corner facing you; keep the remaining wrappers covered with a damp clean kitchen towel. Spoon 1/4 cup of the filling in the lower third of the wrapper. Bring the corner up and over the filling and roll up, folding in the sides as you roll. Dab the top corner with the beaten egg and press to seal the spring roll. Repeat with the remaining wrappers and filling.
Fry the spring rolls in the hot oil, turning occasionally, until golden and crispy and the pork is cooked through, about 5 minutes. Drain on a paper towel–lined baking sheet and serve with hot mustard and/or sweet chile sauce.