Place all the nage ingredients in the bottom of a stainless steel steamer. Bring slowly to a simmer and cook for 10 minutes, skimming off any impurities.
Season the scallops with salt and pepper and place on the top part of the steamer. Cover and steam for 6 minutes. They should be slightly firm and medium rare.
Divide the rice noodles among 4 serving bowls. Place 3 scallops on top and ladle some broth over and around the scallops.
The scallops can also be served as a warm salad over greens with a citrus vinaigrette.