Toshikoshi Soba (New Year's Eve Soba)

Steps

1. Wipe the kombu with a barely damp cloth without washing it: the white powder on the surface carries some of the flavor. Put it in a saucepan with the 1.6 liters of cold water and let it soak for 30 minutes, or overnight in the fridge if you're starting the day before.
2. Heat over medium-low for 10 to 12 minutes. When small bubbles form on the bottom and sides, around 175°F (80°C), and before any simmering, take out the kombu.
3. Bring the water to a boil, turn off the heat, and add the bonito flakes all at once. Let them steep for 2 to 3 minutes, until the flakes have sunk to the bottom. Strain through a sieve lined with a paper towel, without pressing on the flakes: you get a clear, golden dashi.
4. Return the dashi to the saucepan, add the sake and mirin, and simmer for 1 minute. Add the soy sauce and salt, then taste: the broth should be clearly savory, barely sweet, and a little saltier than a soup you'd sip on its own. Keep it covered over very low heat, without letting it boil, so the soy sauce keeps its aroma.
5. Soak the wakame for 5 minutes in a bowl of cold water: it swells and turns green again. Drain it, squeeze it between your hands, and cut it into bite-size pieces if large. Slice the kamaboko 1/4 inch (5 mm) thick and thinly slice the green onions.
6. Bring 3 liters of the cooking water to a rolling boil in a large pot, without salt, and heat the remaining liter in a kettle. Pour a little of this boiling water into the bowls to warm them.
7. Drop the soba into the boiling water, fanning them out, and stir for 30 seconds so they don't stick. Cook according to the package time, usually 4 to 5 minutes, lowering the heat a little if the foam rises. Taste: they should be tender with slight resistance in the center.
8. Drain the soba and rinse them right away under cold running water, rubbing them gently between your hands, until the water runs clear and they no longer feel slimy. Drain well, then pour the rest of the boiling water from the kettle over them to reheat.
9. Empty the water from the bowls and divide the noodles among them. Ladle in the steaming broth to cover, then arrange the kamaboko slices, wakame, and green onion on top. Serve right away with the shichimi togarashi on the table for everyone to add to taste.