Heat the vegetable broth in a pot.
When the broth starts to boil, add the green beans, carrot, sliced shiitake, corn kernels and onion flakes.
Season with salt and pepper.
When the broth starts to simmer, cover the pot, turn down the heat to low and simmer the vegetables and mushroom for five minutes.
Dissolve the starch in a tablespoon of water. Pour into soup. Stir well. Cover the pot once more and continue cooking the soup for another five minutes or until the vegetables are done.
Turn off the heat. Drizzle the beaten eggs into the soup in a circular motion. Let sit for about ten seconds (see two ways to make egg drop soup). Stir.
Serve the corn and mushroom egg drop soup while hot.