Trim pork shoulder completely of exterior fat. Stab slits into the meat with a sharp paring knife and insert peeled slivers of fresh garlic. Rub the outside of the meat with salt, white pepper, and red pepper flakes. Place on a rack in a shallow roasting pan and bake at 350º for 30 minutes per pound or until roast is at least 165º when tested with a meat thermometer. Cool pork and cut into slivers (matchstick size), or shred it if desired.
Shred cabbage on the blade of shredding blade on food processor (cabbage doesn’t have to be cored). Blanch 2 minutes in boiling water. Drain in colander and press down firmly to remove as much excess moisture as possible. Squeezing the blanched vegetables absolutely dry is one of the secrets to these crisp egg rolls. Place cabbage in large bowl with shredded meat.
Cut celery into slivers. Blanch 2 minutes, drain and press firmly. Peel and quarter onions, cut into thin slices and blanch in boiling water for 15 seconds. Drain well but do not press. Grate or shred carrots. Blanch 2 minutes and drain, pressing firmly to remove excess moisture. Add onions and carrots to bowl with meat.
Remove root and wilted tops from green onions. Chop onions and cilantro (stems and all) and add to meat. Add salt, pepper, soy sauce, 5-spice, and sugar. Mix with hands. If the mixture still has a pool of liquid, add up to ½ cup tapioca starch to take up moisture and hold mixture together when it fries. (This filling should fill about 2 packages, or 60 skins.)
Open a package of egg-roll wrappers, remove, and separate all skins in the package and stack on a plate. (Use all skins before opening second package.) Cover with a damp (not wet) kitchen towel.
To make egg rolls, follow the steps below:
1. Turn an egg-roll wrapper onto the counter (so it appears diamond shaped) If any part is torn, place it on the bottom half closest to you. Place 3 tablespoons of filling on the wrapper near the point closest to you.
2. Fold that point over the filling and roll tightly until you’ve gone as far as the two wide points.
3. Paint the remaining sides with egg-white mixture.
4. Fold in both points to enclose mixture.
5. Keep rolling toward farthest point. Paint with more egg white if needed to make the wrapper adhere to itself.
6. The egg roll is made. Set aside and repeat with remaining skins.
Heat vegetable oil in a large skillet or wok to about 335º to 350º . Fry egg rolls until very lightly brown. Drain on a rack set over absorbent paper.
To Freeze Egg Rolls: Place cooled and drained egg rolls on large flat baking pans and freeze until firm. Package in quart freezer bags.
To bake frozen egg rolls: Preheat oven to 400 degrees. Place frozen rolls on a rack in a shallow roasting pan. Bake until golden brown (about 12 minutes). Turn occasionally using folded paper towels to protect your hands.