In a seperate dish wisk eggs together. Slowly add egg mixture to boiling water while slowly stirring.
*Optional: To thicken soup, mix 1 tblspn cornstarch with 1 tblspn cold water until starch dissolves. Lower heat under soup and slowly stir in cornstarch mixture. Return to a simmer and let cook for 1 more minute.
Stir in soy sauce. Serve garnished with sliced scallion.