Bring a large pot of water to a boil. Add noodles, and cook until al dente according to package instructions, about 8 minutes. Drain in a colander, toss with sesame oil, and return to pot. Keep warm.
Meanwhile, in a medium saute pan, heat the vegetable oil over medium heat. Add ginger, shallots, and mushrooms; cook, stirring constantly, until the mixture begins to soften and turn golden brown, about 2 minutes.
Stir chicken stock, vinegar, and soy sauce into pan, and bring to a simmer. Cook until mushrooms are very tender, about 5 minutes. Add spinach and scallions, and stir to combine. To serve, divide noodles among four shallow bowls; ladle soup over noodles.
This was very good and easy to make. I added more liquid (6 cups of water plus some stock concentrate instead of the 2 cups of stock) and added some diced firm tofu with the water. I also added 1 Tbsp of vinegar instead of 1 tsp and 2 Tbsp of soy sauce instead of 2 tsp. I'll definitely make it again.
This soup is one of my favorite. Everyone at home loves it!
Boyfriend didn't really like it. He only ate 8/10ths of this meal.