Sauté your aromatics. Warm the oil or butter in a large pot over medium heat.
Add the onion and cook until soft and translucent, about 3–4 minutes. Stir in the garlic and ginger, and cook for another 30 seconds until fragrant.
Add broth and corn. Pour in the chicken broth and add the corn. Bring to a gentle boil, then reduce to a steady simmer.
Let it cook for 5–7 minutes to blend the flavors.
Stir in the chicken. Add the shredded chicken and soy sauce. Simmer for another 3–5 minutes until everything is heated through and the flavors are balanced. Taste and adjust seasoning with salt and pepper.
Thicken the soup. In a small bowl, mix the cornstarch with water to make a smooth slurry.
Slowly drizzle it into the soup while stirring. Simmer for 1–2 minutes until the soup lightly thickens. If you want it thicker, add another teaspoon or two of slurry.
Create the silky egg ribbons. Reduce the heat to low so the soup is gently simmering.
With one hand, slowly pour the beaten eggs into the pot in a thin stream while stirring the soup in a circle with the other hand. You’ll see delicate ribbons form within 30–60 seconds.
Finish with aroma. Stir in the sesame oil if using. Taste again and adjust seasoning.
The soup should be savory with a hint of sweetness from the corn.
Garnish and serve. Ladle into bowls and top with plenty of sliced green onions. Add a crack of black pepper for a little extra warmth.