Pre-heat oven to 325 degrees Fahrenheit.Marinate the portabello mushrooms in the soya, garlic, shallot, salt and pepper.
Let sit for 30 minutes. Grill or broil 2 minutes per side - then bake in a 325 degrees Fahrenheit oven for 10 minutes - cool - cut into thin strips 1/8".Pat the scallops dry and season with salt and pepper. Sear the scallops in a large non-stick skillet over high for about 1 minute or until browned. Turn. Sear other side for 1 minute or until browned.
Add mushrooms and ponzu sauce. Cook for 1 minute longer, or until the scallops have just warmed through.Use crispy Thai fried noodles, steamed rice or Udon noodles as a garnish.