Cut the tomatoes into spoon-sized pieces.

Slice the white part of the green onion into thin strips about the length of a pinky finger.

Chop the remaining green onion into small pieces for later use.

Beat the egg in a small bowl and set aside.

Heat oil in a pan and sauté the thinly sliced green onion.

Add the tomatoes to the pan and cook until they soften.

Pour water into the pan and bring to a boil.

Add the beaten egg to the boiling soup and gently stir.

Season the soup with salt and black pepper, adjusting to taste.

Simmer for 30 seconds, then add the chopped green onion and turn off the heat.