Step 1Heat oil in a big pot until warm. Add ginger and white part of green onion. Stir a few times until fragrant.Step 2Add ground chicken. Stir and cook until the surface turns white. Add sake and salt. Keep cooking until the chicken is almost cooked through.Step 3Add chicken stock and 2 cups water. Turn to high heat. Cook until bringing to a boil. Add frozen corn and peas. Continue to cook until bringing to a boil again.Step 4While boiling the soup, combine potato starch with 1/4 cup water in a small bowl.Step 5Skim the foam from top of the soup if you want it to look prettier (optional). Turn off heat.Step 6Swirl potato starch slurry into the soup. Mix well.Step 7Put a spatula (or a fork) against one end of the bowl with the egg in it. Slowly drizzle egg into the soup in a swirling motion.Step 8Mix the soup again and taste it with a small spoon (be careful, the soup is very hot!). If the soup is not as thick as you’d like, mix a bit more potato starch slurry and add it into the soup. Add more salt to adjust seasoning if necessary.Step 9Serve warm.