In a medium saucepan, saute ginger and garlic for 1 minute over medium high heat, add two chopped scallions, sliced shiitakes, and broth. Let it come to a simmer.
Put bonito flakes in a bowl or glass measuring cup, add a cup of simmering broth, and let it sit for 5 minutes. Then strain the mixture back into the pot of broth.
Add soy sauce, mirin and white pepper into the broth, stir to combine.
While the broth simmers, cook your noodles in a separate pot of boiling water (according to package directions) and get your toppings ready. Wilt the bok choy or greens in the broth. When ready to serve, remove the broth from the heat. Taste, and adjust salt if needed. See notes.
Divide the cooked noodles among the bowls. Divide the chicken, pull the bok choy out of the broth and add to the bowls with tongs, and ladle the hot broth broth overtop.
Garnish with fresh scallions, soft-boiled eggs, sesame oil, crispy shallots, and sriracha, and red pepper flakes
