Place 2 large frozen tomatoes in a heat resistant bowl, pour boiling water over the tomatoes, let the tomatoes submerge in hot water for 30 seconds.
Transfer the tomatoes out with a ladle or a pair of tongs. Peel the skin easily.(Check this recipe for how to easily peel a fresh tomato.) Set aside on a plate, allow them to thaw a bit before cutting. Wash and finely chop a green onion. Crack 3 medium eggs in a bowl, beat until smooth. Add 3 tbsps of cornstarch and 3 tbsps of cold water to a small bowl, stir until smooth. Set aside.
Cut the tomatoes into bite size chunks.
Heat up the soup pot over medium high heat for about 1 minute, add 2 tbsps of cooking oil to the pot, heat up the oil for 30 more seconds. Carefully pour the tomato chunks to the pot, stir fry over medium high heat for about 1 minute until about 70% of the tomatoes have melted.
Add 4 cups of chicken/vegetable stock (or water) to the pot. Cover the pot with a lid, cook over high heat until boiling.
Open the lid, turn heat to medium low, gradually stir in the cornstarch water. Gently but continuously stir the soup until it turns glossy and thicken.
Add salt and white pepper (or black pepper) to your taste. Gently stir until dissolved.
Use a ladle to pour the eggs to the soup by drawing clockwise circles above the pot. Repeat until you use all the beaten eggs. Turn off the heat.
Add sesame oil, chopped green onions or cilantros to the soup.
Remember to protect your table with trivets if you are going to serve the soup in the pot. Or you can serve the soup in some small soup bowls.