Pork tenderloin or boneless loin, ½lb (250g), thinly sliced across the grain and cut into thin strips
Shiitake mushrooms or button mushrooms, 6oz (185g), stems discarded and caps thinly sliced
Chicken broth or stock, 6cups (48fl oz/1.5l), homemade or purchased
Prepare the seasonings
In a small bowl, combine the soy sauce, Worcestershire sauce, vinegar, sesame oil, chile paste, and cornstarch. Stir to dissolve the cornstarch; set aside.
Cook the soup
Heat a large, heavy saucepan over high heat until hot and add the canola oil. Add the ginger and all but 1tablespoon of the green onions and sauté for about 5 seconds until fragrant. Add the pork and mushrooms and sauté until the pork is just opaque, about 1 minute. Pour in the broth, bring to a boil, and then reduce the heat to low. Give the soup seasonings a quick stir, add to the soup, stir well, and simmer, stirring occasionally, until the soup begins to thicken slightly, about 5 minutes. Ladle into bowls, garnish with the reserved green onions, and serve.