Japanese Natto-Jiru: Fermented Soybean Miso Soup and Regional Breakfast Traditions

Ingredients

• 2 packs (approx. 180 g) natto, fermented soybeans
• 800 ml dashi, prepared, hot but not boiling
• 3 tbsp (approx. 45 g) miso, dissolved — quantity reduced to account for natto's fermented savoury depth
• 150 g tofu, cut into small cubes
• 100 g daikon, peeled and cut into thin half-moons
• 1 stalk (approx. 80 g) leek, trimmed and sliced into thin rounds
• 1 tsp soy sauce, for brightness, added after miso

Method

1. 1
   Place the natto in a suribachi. Work the pestle in firm, circular strokes for 3–5 minutes until the soybeans break down into a rough, cohesive paste and the characteristic strings are fully integrated. The grinding is complete when no whole or clearly intact bean remains — this transformation from whole soybean to paste is the foundation of the dish.
2. 2
   Bring the dashi to a gentle simmer in a medium pot. Add the daikon and cook until just tender — a piece pressed between finger and thumb yields without resistance.
3. 3
   Reduce the heat so the dashi is hot but not boiling. Add the ground natto paste and stir vigorously until it dissolves fully into the broth, producing a cloudy, uniformly thickened liquid. The broth should show no streaks or undissolved clumps.
4. 4
   Add the tofu cubes and leek. Simmer briefly — the leek should soften at the edges while retaining a faint resistance at the centre when pressed.
5. 5
   Remove the pot from direct heat. Dissolve the miso into the broth, stirring until fully integrated. Taste: the broth should read as rich and double-fermented — miso quantity may be reduced if natto depth is already pronounced. Add soy sauce and taste again for brightness.
6. 6
   Ladle immediately into warmed bowls. The soup must be served very hot — at sufficient temperature the cloudy broth holds its integrated character; at low temperature the flavours separate and the preparation loses coherence. Steam rising freely from the bowl is the required condition.