Bring a small pot of water to a boil and cook the egg for 6.5 minutes, then transfer to an ice bath, peel, and slice in half.
Cook the soba noodles according to package directions, drain, and set aside.
Season the pork tenderloin with sea salt and black pepper, then sear in a pan over medium-high heat until cooked through and slice thinly.
In a medium pot, sauté the minced garlic, grated ginger, and sliced shiitake mushrooms in toasted sesame oil until fragrant.
Pour in the pork bone broth and bring to a gentle simmer, then whisk in the miso paste until fully dissolved and smooth.
Place the baby bok choy into the hot broth for 2 minutes until bright green and slightly tender.
Assemble the bowl by placing noodles at the bottom, pouring over the broth and vegetables, and topping with the sliced pork, soft-boiled egg, and scallions.