1. In a pot over medium high heat, saute the tomatoes in sesame oil until tender and partially broken down (3 min).
2. Add the chicken broth, soy sauce, salt and pepper and bring to a boil.
3. Mix the cornstarch with water and pour it into the pot.
4. Beat the eggs slightly (you want some of the white and yellow to still be separate); when the soup is boiling, stir to create a whirlpool and slowly drizzle in the eggs (this will create egg ribbons in the soup).
5. Add the scallions and vinegar, cook for 1-2 more minutes and turn off the heat; taste and adjust seasoning if needed.
6. Serve with fresh cilantro on top and enjoy!
