Soak mushrooms and rice vermicelli in steaming hot water for 5-7 minutes. Chop mint, cilantro and garlic. Cut the onion into eights and slice *very* thin. Drain and squeeze out the mushrooms, and cut into thin slices. Drain the vermicelli and cut into 1" pieces. Add all these ingredients into a bowl with pork sausage meat, egg and seasonings. Blend well with hands. Let sit two hours minimum for best flavor.
Mix 1 T flour and a little more than 1 T water to make a paste.
On a damp cloth, lay two square egg roll wrappers so they are overlapping; dab paste where they overlap to hold them together. Place filling down the length of the overlap. Fold edges of dough over ends of filling, then roll dough over length of filling, using more paste to secure the far corner of the wrapper to the roll. Fry for 4-6 minutes over medium heat; check on first nem to ensure the pork has cooked properly and is no longer pink. Serve hot with sweet chili sauce.