Place the bean sprouts in a colander.  Pour a pot of boiling water over them; then immediately run them under some cold water.  Next, set up five bowls containing the following: (1) the pork, (2) the shrimp, (3) the sprouts, celery and green onions, (4) the oyster sauce and soy sauce and (5) the cornstarch and water.  Heat the oil in a wok over high heat.  Add the pork and stir-fry for 2 minutes.  Add the shrimp and stir-fry for 1 minute.  Add the vegetables and stir-fry for 2 minutes.  Add the sauces and stir-fry until well blended.  Pour the filling into a colander and allow it to drain.  When the filling mixture is cool, here's how you roll them: (1) lay an egg roll wrapper flat in front of you like a baseball diamond with home plate closest to you, (2) place 2 Tbsp. of the filling mixture between the pitcher's mound and home plate, (3) begin a snug roll starting at home plate and rolling towards 2nd base, (4) stop when the roll reaches the pitcher's mound, (4) brush the cornstarch mixture along the 1st-to-2nd-to-3rd baselines, (5) fold the 1st and 3rd base corners up and across the roll so the ends of the roll are sealed snug, and (6) finish by rolling until you reach 2nd base.  Fry in 375 degree oil until light brown.  Fry a 2nd time until fully browned just before serving.  More about egg roll wrappers in "Dumpling Techniques" in Miscellaneous.