In a large pan, bring 4 cups water, Kombu and the ginger to a boil. Reduce heat and simmer for a few minutes.

Turn off heat. Add Bonito flakes and keep it aside for a few more minutes. Strain both through a strainer into a bowl.

Rinse pot and then pour in broth. Add carrots and leek. Simmer for at least a couple of minutes. Now add scallops and halibut fillets. Simmer for a minute and then add shrimp. Cook for a couple of more minutes.