1Prepare the dashi stock: Add Water and Kombu to a large pot. Let the Kombu soak for 15 minutes. Heat the pot over medium heat, bringing the Water just to a simmer. Remove the Kombu just before the Water boils. Add Katsuobushi to the simmering Water, turn off the heat, and let it steep for 5 minutes. Strain the dashi through a fine-mesh sieve, discarding the Katsuobushi. You should have approximately 1200 grams of dashi stock.
3Sear the duck breast: Place the Duck breast skin-side down in a cold pan. Turn the heat to medium-low and slowly render the fat for 8-10 minutes until the skin is crispy and golden brown. Flip the Duck breast and sear the meat side for 2-3 minutes until lightly browned. Remove the Duck breast from the pan and let it rest for 5 minutes before slicing thinly against the grain.