3 Tbs Finely chopped onion
1 small Garlic clove, minced
3/4 tsp Dried red pepper flakes
1 tsp Vegetable oil
3 Tbs water
1 Tbs Creamy peanut butter
1 Tbs Hoisin sauce
1 tsp Tomato paste
3/4 tsp Sugar
4 oz Bean thread or rice noodles (cellophane noodles)
1 Tbs Vegetable oil
1/2 lb Shiitakes, remove stems and slice remaining portion
2 Tbs Soy sauce
1 Large Sweet potato, steamed and cut into batons
1 lb Asparagus, trimmed, steamed and halved lengthwise
12 8-inch Rice-paper rounds, plus additional in case some tear
1. Cook onion, garlic and red pepper flakes in oil in a small heavy saucepan over moderate heat, stirring until pale golden, about 4 minutes. Whisk in remaining sauce ingredients. Simmer, whisking, for 1 minute, and then cool.
2. Cover noodles with boiling-hot water and soak 15 minutes, then drain well in a sieve. Pat dry between paper towels and toss with vinegar and salt to taste.
3. Heat vegetable oil in sauté pan. Add shiitakes and soy sauce. Cook for 2-3 minutes. Transfer to bowl.
4. Put a double thickness of paper towel on a work surface and fill a shallow baking pan with warm water. Soak 1 rice-paper round (make sure there are no holes) in warm water until pliable, 30 seconds to 1 minute, then transfer to paper towels.
5. Top rice paper round with even parts noodles, sweet potato, asparagus and shiitakes. Then fold in sides and continue rolling. Transfer summer roll to a plate and cover with dampened paper towels.
6. Continue until all of the rice wrappers have been used. Serve rolls halved on the diagonal.