Combine shiitake mushrooms and 3 cups of the chicken stock in a small saucepan and bring to a simmer. Remove from heat and let stand until mushrooms are tender and broth is flavorful, about 30 minutes. Remove mushrooms and discard stems. Thinly slice caps and reserve. Strain
broth through a fine mesh sieve
, combine with the remaining chicken stock and set aside.
In a medium saucepan
heat the vegetable oil
and, when hot, add the ginger, garlic and crushed red pepper
; cook for 2 minutes, or until fragrant. Add the chicken stock
and reserved shiitakes
and bring to a simmer. Cook for 30 minutes. Add the pork and tofu
and stir to combine. In a small bowl or cup, combine the lime
juice and cornstarch and stir until smooth. Whisk
the cornstarch mixture into the hot soup and bring to a boil. Reduce heat to a simmer
and cook for 5 minutes. Add the soy sauce
and sesame oil and serve the soup
, drizzled with hot chile oil, to taste, and garnished with some of the sliced scallions.