How to Make It
Bring the stock, ginger, and 1 teaspoon salt and 1/2 teaspoon pepper to a boil in a medium saucepan.
Stir together the soy and corn starch, then whisk into the broth and boil until the soup is slightly thickened, 1 to 2 minutes.
Remove the saucepan from heat. Whisk together the eggs, sesame oil, and 1/2 teaspoon salt, then pour the eggs into the hot broth in a slow stream, whisking constantly to scatter the eggs as they cook.
Stir in the edamame and cook 2 minutes, then season the soup with salt to taste.
Serve the soup topped with the scallions.