I Made 400-Year-Old Miso Soup • Tasty

Ingredients

• 1 cup Dried Soybeans (about 200 g, rinsed and soaked overnight)
• 1/4 cup Koji (Rice Inoculated with Aspergillus oryzae) (dry, store‑bought or home‑grown spores)
• 2 tablespoons Sea Salt (non‑iodized, fine grain)
• 1 piece Kombu (Dried Kelp) (about 10 g, for dashi stock)
• 1/2 cup Bonito Flakes (Katsuobushi) (lightly toasted for dashi)
• 200 g Silken Tofu (cut into 1‑inch cubes)
• 1 tablespoon Dried Wakame Seaweed (rehydrated in water for 5 min, drained)
• 2 stalks Green Onions (Negi) (thinly sliced for garnish)
• 4 cups Water (filtered)

Instructions

1. Soak Soybeans

   Place the dried soybeans in a large bowl, cover with plenty of water and let soak for at least 12 hours or overnight.

   Time: PT12H

2. Cook Soybeans

   Drain the soaked beans, transfer to a large pot, cover with fresh water and simmer over medium heat until very tender, about 1 hour.

   Time: PT1H

   Temperature: 90°C

3. Mash Soybeans

   Drain the cooked beans and, while still warm, mash them in a mortar and pestle (or pulse briefly in a food processor) into a coarse paste.

   Time: PT10M

4. Prepare Koji‑Salt Mix

   In a small bowl combine the dry koji with the sea salt, mixing until evenly distributed.

   Time: PT5M

5. Combine Soybean Paste with Koji‑Salt

   Add the koji‑salt mixture to the mashed soybeans and knead with clean hands until a uniform, slightly sticky dough forms.

   Time: PT10M

6. Pack Miso for Fermentation

   Transfer the miso dough into a sterilized fermentation container, pressing down firmly to eliminate air pockets. Smooth the top and cover with a layer of salt, then seal with cheesecloth and a lid.

   Time: PT5M

7. Ferment Miso

   Allow the packed miso to ferment undisturbed for 3 to 6 months. Check periodically for surface mold; scrape off any white surface growth.

   Time: PT0S

8. Soak Kombu

   Place the kombu in 4 cups of cold water and let soak for at least 30 minutes (or overnight for deeper flavor).

   Time: PT30M

9. Make Kombu Dashi

   Heat the kombu‑water mixture over low heat until just before boiling (around 60‑70°C), then remove the kombu and discard.

   Time: PT10M

   Temperature: 70°C

10. Add Bonito Flakes

    Add the bonito flakes to the hot kombu stock, bring to a gentle boil for 2 minutes, then turn off the heat and let steep for 5 minutes.

    Time: PT7M

    Temperature: 90°C

11. Strain Dashi

    Strain the broth through a fine mesh strainer or cheesecloth into a clean pot, pressing the solids to extract maximum flavor.

    Time: PT5M

12. Incorporate Miso

    Turn the dashi to a low simmer (no rolling boil). Scoop the fermented miso paste (about 2 tablespoons per serving) into a small bowl, add a ladle of hot dashi and whisk until smooth, then stir the mixture back into the pot.

    Time: PT5M

    Temperature: 80°C

13. Add Tofu and Wakame

    Gently add the cubed silken tofu and rehydrated wakame to the soup, warm for 2‑3 minutes without boiling.

    Time: PT5M

    Temperature: 80°C

14. Finish and Serve

    Turn off the heat, sprinkle sliced green onions over each bowl, and serve immediately.

    Time: PT2M

Nutrition Facts

Calories

90

Protein

6 g

Carbohydrates

8 g

Fat

3 g

Fiber

1 g

Ingredient Substitutions

• Instead of Dried Soybeans: Soybean flour (for a quicker version)
• Instead of Koji (Rice Inoculated with Aspergillus oryzae): Commercial miso paste (if skipping fermentation)
• Instead of Sea Salt: Kosher salt (adjust amount)
• Instead of Kombu (Dried Kelp): Dried kelp strips
• Instead of Bonito Flakes (Katsuobushi): Dried shiitake mushrooms (vegetarian dashi)
• Instead of Silken Tofu: Firm tofu (will hold shape better)
• Instead of Dried Wakame Seaweed: Nori strips
• Instead of Green Onions (Negi): Chives

Equipment Needed

• Large Pot
• Saucepan
• Mixing Bowl
• Mortar and Pestle
• Fermentation Container
• Cheesecloth
• Fine Mesh Strainer
• Ladle
• Cutting Board
• Chef’s Knife
• Measuring Cups and Spoons

Critical Steps — Do Not Skip

• Soak soybeans overnight (Step 1)
• Cook soybeans until very tender (Step 2)
• Pack miso tightly to eliminate air (Step 6)
• Ferment miso for at least 3 months (Step 7)
• Do not boil kombu; keep temperature below 80°C (Step 9)
• Do not boil after adding miso paste (Step 12)

Chef Tips from the Video

• Use high‑quality kombu with a thick, glossy surface for the richest umami.
• For a smoother miso paste, process the mashed soybeans in a food processor after the initial hand‑mash.
• A pinch of mirin can be added to the dashi for a subtle sweetness if desired.

Troubleshooting

Storage

Refrigerator: Fermented miso can be stored in a sealed container for up to 1 year. Dashi broth keeps 3 days refrigerated.

Freezer: Miso paste freezes well for up to 6 months; dashi freezes for 2 months.

Room temperature: Do not store miso at room temperature after fermentation; keep sealed in a cool pantry only during the fermentation period.

Make-Ahead Tips

• Ferment the miso paste months in advance; it improves with age.
• Prepare dashi broth a day ahead and refrigerate; reheat gently before adding miso.
• Pre‑cut tofu and rehydrate wakame; store them separately in airtight containers.

Frequently Asked Questions