Add 3 cups of water, the soup stock pack, and kombu to a pot. Bring to a boil.

Mix 1 tbsp cornstarch with 1 tbsp water to create a slurry. Beat 2 eggs in a separate bowl.

Slice the shiitake mushrooms and chop the green onions. Prepare all ingredients for easy cooking.

Once the broth is boiling, remove the kombu and continue boiling the soup stock pack for a few more minutes. Add the sliced shiitake mushrooms.

Stir in the cornstarch slurry while continuously stirring the soup to thicken it.

Reduce the heat and slowly pour the beaten eggs around the edges of the pot. Let them set slightly before stirring.