Bring a small pot of water to a boil, add the egg, and cook for 6.5 minutes before transferring immediately to an ice bath to stop the cooking.
Cook the soba noodles in a separate pot of boiling water according to package directions, then drain and set aside.
Season the thinly sliced pork tenderloin with sea salt and black pepper.
Heat the sesame oil in a large pot over medium-high heat and sear the pork slices until golden brown and cooked through, then remove and set aside.
In the same pot, sauté the minced garlic, grated ginger, and sliced shiitake mushrooms for 2 minutes until fragrant and softened.
Pour in the beef broth and tamari, bringing the liquid to a gentle simmer to meld the flavors.
Add the baby bok choy to the simmering broth and cook for approximately 2 minutes until the leaves are wilted and the stems are just tender.
Place the cooked soba noodles and seared pork into a large bowl, pour the hot broth and vegetables over the top, and garnish with the peeled and halved soft-boiled egg.