Bring a pot of water to a boil and cook the soba noodles according to package directions, adding the chopped bok choy for the last 60 seconds of cooking.
Drain the noodles and bok choy, then rinse briefly under warm water to prevent sticking.
In a small bowl, whisk together the tahini, tamari, rice vinegar, chicken bone broth, and chili oil until the sauce is smooth and emulsified.
Heat the toasted sesame oil in a large skillet over medium-high heat.
Add the ground pork to the skillet, breaking it up with a spatula, and cook until browned and cooked through.
Stir in the minced ginger, garlic, and ground Sichuan peppercorns, sautéing for 1 minute until fragrant.
Pour the prepared sauce into the skillet with the pork and stir to combine, allowing it to simmer for 1-2 minutes until slightly thickened.
Add the cooked noodles and bok choy to the skillet, tossing well to coat everything in the spicy sauce.
Garnish with sliced green onions before serving warm.