3Prepare dashi: Wipe 5g kombu with a damp cloth. Place the kombu in a pot with 500g cold water. Heat gently; just before boiling, remove the kombu. Bring the water to a boil, add 10g katsuobushi, immediately turn off the heat, and let steep for 5 minutes. Strain the dashi through a fine-mesh sieve, discarding the katsuobushi.