Wash the pork, then finely mince it or blend it in a food processor until very smooth.
Finely chop all the vegetables for the filling: onion, carrot, kohlrabi, scallions, cilantro, and bean sprouts.
Julienne the carrot and kohlrabi into strips about 1.5 inches (3–4 cm) long.
Soak the glass noodles in warm water (about 86°F/30°C) for 5 minutes until soft, then cut into short pieces.
Soak the shiitake and wood ear mushrooms in hot water until they expand. Remove the tough stems and finely chop the mushrooms.

Place all the prepared filling ingredients into a large mixing bowl. Add 1 tablespoon vegetable oil, black pepper, fish sauce, seasoning, and bouillon powder. Crack in 2 eggs.

Lay out the spring roll wrappers (it’s best to do this on a flat surface like a cutting board or tray). Dip your fingers in beer or vinegar and lightly moisten the wrappers to help them crisp up. Place a portion of the filling onto the wrapper, roll it up once to cover the filling, then fold in both sides.
Continue rolling until the filling is completely wrapped.
Make sure to roll all the spring rolls to the same size and roll them tightly so they cook evenly and don’t break apart when frying.

Heat vegetable oil in a pan until hot. Fry the spring rolls once until lightly golden. When ready to serve, fry them a second time until evenly golden and crispy.

A key to delicious nem rán is the dipping sauce. The classic ratio for the sauce is: 1 part sour, 1 part sweet, 1 part fish sauce, and 3 parts water. When serving, add finely chopped garlic and chili, and sprinkle with a little black pepper for the perfect dipping sauce.