Bring a small pot of water to a boil and cook the soba noodles according to package directions, then drain and set aside.
Slice the pork tenderloin into very thin strips and season lightly with sea salt and black pepper.
In a medium pot, heat the toasted sesame oil over medium-high heat and sear the pork strips until golden brown and cooked through.
Add the minced garlic, grated ginger, and sliced shiitake mushrooms to the pot, sautéing for 2 minutes until the aromatics are fragrant.
Pour in the chicken bone broth, tamari, and sriracha, bringing the liquid to a gentle simmer.
Stir in the chopped bok choy and cook for 2-3 minutes until the leaves are wilted but the stems remain crisp.
Place the cooked soba noodles into a large bowl and ladle the hot pork and spicy broth over them.
Garnish with sliced green onions and serve immediately.