Bring a small pot of water to a boil and cook the soba noodles for 4-5 minutes until al dente, then drain and rinse under cold water.
Pat the ahi tuna steak dry with paper towels and season both sides with sea salt and black pepper.
Spread the sesame seeds on a flat plate and press the tuna steak into the seeds until the exterior is evenly coated.
In a small bowl, whisk together the tamari, wasabi paste, and freshly grated ginger to create the zesty glaze.
Heat the avocado oil in a cast-iron skillet over high heat until just beginning to smoke.
Sear the tuna for 45-60 seconds per side for a rare center, ensuring the sesame seeds are golden and fragrant.
Remove the tuna from the pan and let it rest for 2 minutes before slicing into thin strips.
Toss the chilled soba noodles with the shelled edamame and half of the wasabi glaze.
Plate the sliced tuna over the noodles and drizzle with the remaining glaze to serve.