Sansai Soba

1. Prepare Dashi: Place kombu and 1000 grams water in a pot. Heat gently over medium-low heat. Just before the water boils, remove the kombu. Bring the water to a boil, then turn off the heat. Add katsuobushi and let it steep for 5 minutes. Strain the dashi stock through a fine-mesh sieve lined with a paper towel or cheesecloth. Set aside 800 grams of dashi stock for the tsuyu.

2. Prepare Sansai: If using fresh fuki, warabi, and zenmai, blanch them briefly in boiling water, then refresh in cold water. Squeeze out excess water and cut into 3-4 cm lengths. If using dried, rehydrate according to package instructions and then cut. Slice aburaage into thin strips. In a small pot, combine 100 grams water, 15 grams koikuchi soy sauce, 10 grams mirin, 5 grams sake, and 5 grams sugar. Bring to a simmer. Add the prepared fuki, warabi, zenmai, and aburaage to the pot. Simmer gently for 10-15 minutes until the liquid is mostly absorbed and the vegetables are tender and flavorful. Set aside.

3. Prepare Soba Noodle Soup (Tsuyu): In a separate pot, combine 800 grams dashi stock, 60 grams koikuchi soy sauce, 40 grams mirin, 20 grams sake, and 2 grams salt. Bring the tsuyu to a gentle simmer over medium heat. Do not boil vigorously. Keep warm.