Prepare the dashi broth by gently heating water with kombu seaweed until nearly simmering, then remove the kombu and steep bonito flakes if using. This creates the savory base that gives the soup authentic Japanese flavor.
Add mushrooms to the broth and simmer until tender before carefully adding tofu cubes. Gentle cooking keeps the tofu soft while allowing the mushrooms to release their earthy flavor into the broth.
Dissolve the miso paste in a small bowl with warm broth before stirring it into the pot. Mixing it separately prevents clumps and helps the soup stay smooth and balanced.
Season the soup with soy sauce and sesame oil, tasting carefully as you go. Small adjustments help you create the perfect savory balance without overpowering the broth.
Stir in green onions and nori strips just before serving so they stay fresh and flavorful. Serve the soup hot with extra garnishes if desired.
