Kenchinjiru: Zen Buddhist Root Vegetable Soup and Its Role in Japanese Cold-Season Cooking

Ingredients

• For the dashi
• 1 piece (10 cm) kombu, wiped clean with a damp cloth
• 4 dried shiitake mushrooms, soaked in cold water until softened; soaking liquid reserved
• 300 g firm tofu, pressed between weighted plates for 20 minutes, then torn into irregular pieces
• 150 g gobo (burdock root), scrubbed, torn or snapped into irregular pieces, held in cold water to prevent browning
• 150 g daikon, peeled, torn or cut into irregular chunks
• 100 g carrot, peeled, torn or snapped into irregular pieces
• 150 g satsumaimo (Japanese sweet potato), scrubbed, torn into irregular chunks
• 100 g renkon (lotus root), peeled, torn or broken into irregular pieces, held in acidulated water
• 100 g konnyaku, torn into irregular pieces by hand; briefly blanched and drained
• 2 tbsp sesame oil
• Seasoning
• 2 tbsp light soy sauce (usukuchi)
• 2 tbsp mirin
• 2 tbsp sake
• To finish
• 1 tsp kuzu (arrowroot), dissolved in 1 tbsp cold water
• 1 small piece yuzu zest, or a few drops of yuzu juice, added just before serving

Method

1. 1
   Make the dashi. Combine the kombu and soaked shiitake mushrooms with their strained soaking liquid in a pot; add enough cold water to reach approximately 1.2 litres total. Bring slowly to just below a simmer over medium-low heat. Remove the kombu before the water boils. Allow the shiitake to steep a further 10 minutes, then remove and reserve. The finished dashi should be pale amber, clear, and carry a clean oceanic-mineral scent.
2. 2
   Press the firm tofu between two weighted plates for 20 minutes. Drain off expelled water. Tear the tofu by hand into irregular pieces of roughly 3–4 cm. Pat all torn vegetables and tofu dry. Dryness at this stage is essential: surface moisture will steam rather than sear.
3. 3
   Heat the sesame oil in a heavy pot or donabe over medium-high heat until it shimmers. Add the gobo and renkon first — these are the densest vegetables and require the longest cooking time. Stir-fry, turning the pieces, until the irregular torn surfaces take a light golden colour and the kitchen fills with a toasted, nutty sesame aroma. This is the step on which the dish lives or dies: skipping or shortening this stir-fry produces a thinner, less complex soup that cannot be corrected by seasoning at a later stage. The Maillard reaction on the vegetable surfaces creates depth that plain simmering cannot achieve.
4. 4
   Add the daikon, carrot, satsumaimo, konnyaku, and reserved shiitake (sliced or torn) to the pot. Continue stir-frying, turning all pieces, until the sesame oil has coated every surface and the vegetables show the first signs of translucency at their edges — approximately 3–4 minutes. Add the torn tofu last and turn gently once or twice to coat without breaking.
5. 5
   Pour in the dashi and bring to a gentle simmer. Add the sake and mirin. Skim any foam that rises in the first minutes. Reduce the heat to maintain a calm simmer — not a rolling boil, which would cloud the broth and break the tofu. Simmer until gobo and renkon are fully tender when pressed with a finger and offer no resistance at their centres — approximately 20–25 minutes.
6. 6
   Season with the light soy sauce. Taste: the soup should be deeply savoury but not heavily salted — the root vegetables provide natural sweetness that balances the seasoning without requiring aggressive correction. Adjust with small additional amounts of soy only if necessary.
7. 7
   Stir the dissolved kuzu into the simmering soup in a slow stream, stirring gently. The broth will shift to a silky, lightly thickened consistency within one minute. Add the yuzu zest or a few drops of yuzu juice directly to the pot or to each bowl at service. The finished soup should be aromatic, the broth clear-to-lightly-glossy, and the vegetables intact in their irregular forms.