In a bowl, mix together the ground pork or shrimp with shredded carrots, cabbage, bean sprouts, chopped wood ear mushrooms, onion, garlic, fish sauce, soy sauce, sugar, and black pepper. Let the mixture marinate for about 15-20 minutes to allow the flavors to meld.
Prepare a shallow dish filled with warm water. Dip one spring roll wrapper into the water for about 5-10 seconds until it softens. Place the wrapper on a clean surface.
Spoon about 2-3 tablespoons of the filling onto the bottom third of the wrapper, leaving some space on the sides. Fold the bottom edge of the wrapper over the filling, then fold in the sides, and roll tightly to enclose the filling completely.
Heat vegetable oil in a deep skillet or pot over medium heat until it reaches 350°F (180°C). Carefully place the spring rolls into the hot oil, seam side down, in batches to avoid overcrowding. Fry for 3-4 minutes, turning occasionally, until they are golden brown and crispy.
Remove the fried spring rolls with a slotted spoon and drain them on a plate lined with paper towels to remove excess oil.
Serve the Vietnamese Fried Spring Rolls hot with lettuce leaves, fresh herbs, and dipping sauce on the side.