Clean the kombu with a dry cloth if needed. Cut into thirds and soak in water for 1 hour. Heat gently, remove kombu before boiling, then add bonito flakes. Let sit for 5–6 minutes until bonito sinks, then strain to make dashi.

Grate the yam. Remove shiitake stems, chop them finely, and mix with cornstarch in a bowl.

Chop the peeled shrimp into a paste using a knife until sticky.

Mix shrimp paste, grated yam, egg white, and salt in the bowl until sticky and well combined.

Heat the dashi with remaining ingredients. Add shiitake caps and spoon shrimp mixture into bite-sized portions. Cook gently for 2 minutes over low heat.