Bring a small pot of water to a boil and cook the egg for 6 minutes and 30 seconds, then immediately transfer to an ice bath to cool.
Cook the soba noodles in a separate pot of boiling water according to package directions, then drain and set aside.
In a skillet over medium-high heat, cook the diced pork belly until the fat renders and the edges are golden and crispy.
Remove the pork belly from the pan, leaving the rendered fat, and sear the thinly sliced pork tenderloin seasoned with salt and pepper for 2-3 minutes per side.
In a medium saucepan, bring the chicken bone broth, tamari, garlic powder, and ginger powder to a gentle simmer.
Remove the broth from the heat and slowly whisk in the nonfat Greek yogurt and toasted sesame oil until the liquid is smooth and creamy.
Place the spinach and noodles in a large bowl, pour the hot broth over them to wilt the greens, and top with the sliced pork tenderloin, crispy pork belly, halved egg, and sliced green onions.