In a bowl, mix the pork with the garlic, scallion, 1/2 teaspoon of the sugar, 1 1/2 tablespoons nuoc mam, the egg and the cornstarch. Leave the mixture in the refrigerator for 30 minutes. Meanwhile, prepare a charcoal fire.
When you are ready to cook the pork, shape the mixture roughly into 6 ping-pong sized balls. Lightly oil a steamer tray and steam the pork balls for 5 minutes. Transfer the partially cooked pork balls to a hot grill fire. Cook for 10 minutes, turning occasionally so all sides of the balls get golden brown. Remove the pork balls from the fire, cut them in half, and return them to the fire, cut side down. Grill them for 5 more minutes. Remove the pork and when it is cool enough to handle, cut it in shreds roughly 1 1/2 inches thick. Reserve.
Bring a few quarts of salted water to the boil. Plunge the shrimp into the boiling water and turn the heat off. Remove the shrimp form the water when just cooked (2 to 3 minutes). In a bowl, mix together the remaining 2 tablespoons of fish sauce and the remaining tablespoon of sugar. When the shrimp are cool enough to handle, peel them and slice them in half the long way (cutting each shrimp into 2 thin, C-shaped pieces). Reserve the shrimp and fish sauce sugar mixture.
Submerge 1 sheet of banh trang in a basin of warm water for 2 to 3 seconds, then remove it immediately. Try to dip all of it into the water simultaneously and handle it carefully so it doesn't tear. Place the sheet on a dry towel.
Roll the sheet right on the towel: About 1-inch above the lower edge of the sheet, spread out 1/8 cup of shredded lettuce. Leave a 1 1/2-inch gap between the left edge of the sheet and the lettuce and the same between the right edge of the sheet and the lettuce. Define a rectangle with the lettuce that is about 5 inches wide and 3 inches long toward the center of the sheet. Now evenly top the lettuce rectangle with 1/8 of the bean sprouts, 1/8 of the shredded carrot and 1/8 of the peanuts. Evenly distribute 1/8 of the grilled pork shreds over the rectangle. Tear 5 to 6 mint leaves, and an equal amount of cilantro and distribute those over the rectangle. Top everything with a few sprinkles of nuoc mam.
Carefully pick up the right edge of the sheet and fold it toward the center of the filling. Make sure the folded sheet is even and uncreased. Do the same with the left edge of the sheet. The rectangle of filling should now be covered by the folded sheet with the left and right edges meeting each other at the center of the rectangle. Pick up the bottom edge of the sheet and start rolling away from you, making sure to tuck the filling in tightly as you roll. When you have rolled about halfway to the top of the sheet, dip the shrimp halves in the reserved fish sauce-sugar mixture. Place 2 shrimp halves along the cylinder that you have half-rolled and keep on rolling until a fully rolled cylinder has been formed. Place it under a damp towel. Repeat the process 7 more times to make 7 more rolls. Serve immediately or cover the rolls with damp towels and
Recipe courtesy of David Rosengarten