Soba Noodle Soup

To Make the Soba Broth from Scratch (without mentsuyu)

1. Soak 1 piece kombu (dried kelp) in 3 cups water overnight (optional, if you have time). Otherwise, soak the kombu for at least 30 minutes.
2. Transfer the kombu and water into a saucepan. Bring the water to a boil. When it’s almost boiling, remove the kombu from the water and reserve it for another use (see below*). If you‘re vegan or vegetarian, this kombu dashi is your soup base, so skip the next step.
3. Add 1 cup katsuobushi (dried bonito flakes) and simmer for 30 seconds. Then turn off the heat and let the katsuobushi sink to the bottom of the pot. Let the katsuobushi steep for about 10 minutes.
4. Strain the liquid in a fine-mesh sieve over another saucepan (I also placed a paper towel in the bottom of the sieve beforehand to help gather the bonito flakes). Gently twist and squeeze the paper towel to release any remaining dashi into the saucepan. Reserve the katsuobushi for another use (see below*). Now you have awase dashi.
5. Add 1 Tbsp sake, 2 Tbsp mirin, 2 Tbsp soy sauce, and 1 tsp Diamond Crystal kosher salt to the dashi and bring the broth to a simmer. Cover with the lid to keep hot and set aside.
6. *Use the spent kombu and katsuobushi to make Homemade Furikake Rice Seasoning. You can also save the drained katsuobushi and kombu in the freezer until you‘re ready to make the furikake.

To Prepare the Toppings

1. Please note that there is a variety of topping options (including vegan) available for Soba Noodle Soup. Read more about other choices in the blog post.
2. Bake 2 pieces frozen shrimp tempura, flipping halfway through, at 400ºF (200ºC) for 20 minutes, or according to the package instructions.
3. Insert a knife at the bottom of 4 slices kamaboko (fish cake) to separate it from the wooden board. Then cut the kamaboko into ¼-inch slices.
4. Slice 1 green onion/scallion thinly and cut 2 oz komatsuna into 2-inch pieces.
5. Boil the komatsuna in salted water. I first boil the hard stems of the komatsuna since they take longer to cook. Then, I add the leafy green parts later. Once they are tender, take the komatsuna out and soak in ice water to stop the cooking. Drain well.

To Cook the Soba Noodles

1. Meanwhile, reheat the soup broth on low heat and boil two large pots of water—one for cooking the soba noodles and the other for warming up the noodles after rinsing them (the second is optional; see my shortcut below). Unlike pasta, you do not need to add salt to the cooking water. Once the water in the first pot is boiling, cook 7 oz dried soba noodles (buckwheat noodles) for 30 seconds less than the package instructions. Mine says to cook for 4 minutes, so I cook for 3 minutes and 30 seconds.
2. Drain the soba noodles in a colander and rinse them with your hand under cold running water to get rid of the starch. Next, warm up the noodles again. My Shortcut Way: Switching to hot running water, quickly rinse the noodles in the colander to warm them up. Shake and drain completely. Transfer the warmed noodles to individual bowls.
3. The Traditional Way: After rinsing the soba noodles under cold running water, drain and transfer them to the second pot of boiling water for just 5–8 seconds to quickly warm them up. Then, drain and transfer the warmed noodles to individual bowls.

To Assemble

1. Pour the piping-hot soba broth over the noodles and garnish with the toppings of your choice. Sprinkle shichimi togarashi (Japanese seven spice) on top if you like it spicy. Serve immediately.

To Store

1. You can keep the leftover soup, noodles, and toppings separately in airtight containers and store in the refrigerator for 2 days.

To Make the Quick Soba Broth (with Concentrated Mentsuyu; Optional)

1. Follow your mentsuyu (noodle soup base) bottle instructions for the correct dilution ratio for soba broth. I use a dilution ratio of 1 to 7 for kaketsuyu (noodle broth).
2. In a medium saucepan, combine 2⅓ cups water, ⅓ cup mentsuyu (concentrated noodle soup base), and 1 Tbsp mirin and mix well. Bring the mixture to a gentle simmer over medium heat. Cover with a lid and turn off the heat. The soba broth is ready to use.