Soak wood ear mushrooms in hot water to rehydrate and plump up, about 20 minutes. Rinse well and chop.
Grind mushrooms, taro, and onions in a food processor. Saute minced vegetables until caramelized.
Combine cooked vegetables with ground pork, shrimp, green onions, fish sauce, and peppers.
Dissolve sugar in hot water. Moisten rice paper, add filling, and roll up to form egg rolls.
Fry egg rolls in hot oil until crispy and cooked through. Drain on a wire rack.
Make the nước chấm by boiling fish sauce, vinegar, sugar, and water. Add minced garlic and chilis.