Ingredients
2 large pieces kombu, approximately 10-by-4-inches each, gently wiped with a damp towel
3 cups packed katsuobushi (dried bonito flakes)
Preparation
Place kombu and 9 cups water in a large pot; let soak at room temperature for at least 20 minutes and up to overnight.
Place pot over high heat and bring to a boil. Remove kombu and discard. Reduce heat to a simmer and gently stir in katsuobushi. Let simmer for 10 minutes. Strain through a fine mesh sieve into a 2-quart container.
