Wash the king oyster mushrooms (see my blog post for tips on cleaning mushrooms). Slice the stems of the mushrooms into 1-inch discs. Save the mushroom caps for marinating and eating as well. No need to waste food.
To make the miso marinade, combine the mirin, water, miso paste, maple syrup and tamari ingredients listed under the "For the Vegan Scallops" heading in your food processor.
Lay the mushroom discs in a shallow baking pan and cover with the marinade. Cover and refrigerate for at least 30 minutes, pausing to flip the mushrooms periodically.
While the mushrooms are marinating, make the miso dressing for your soba noodles by combining the tamari, rice vinegar, sesame oil and miso paste ingredients listed under the "For Your Soba Noodles" heading in your small food processor. Steam the asparagus. Set both aside.
After the mushrooms have finished marinating, heat enough grapeseed oil to cover the bottom of a large cast iron skillet. When hot, place each mushroom in the oil and sear each side for approximately 3 minutes. Be careful as the water from the marinade might spatter when the mushrooms are added to the pan.
Prepare the soba noodles in accordance with the package directions. If you’ve never made soba noodles before, I encourage you to read my blog post on how to make them.
Toss the cooked soba noodles in the miso dressing and top them with the vegan scallops, the steamed asparagus, some sesame seeds and thinly sliced scallions.