Bring a medium-sized pot of water to a boil. Add golden needle mushrooms and cook over medium heat for 1 minute, until the mushrooms are just cooked through. Transfer mushrooms to a colander and run tap water over them to stop cooking. Drain and set aside.
Prepare the rest of the vegetables. Combine mushrooms, cucumber, jalapeno, and garlic in a bowl.
Mix light soy sauce, sugar, salt, and sesame oil in a small bowl.
Right before serving, pour sauce over the salad and mix well. Serve immediately as a side or an appetizer.