First, add the water to a pot and bring to the boil. Reduce to a simmer, add the konbu piece and continue to simmer for 15 minutes. This will give your broth a subtle yet delicious umami flavour.
Cut the tofu into six pieces and add to the broth. Pop on the cover and continue to simmer for 6 minutes.
Prepare the dipping sauce. Combine soy sauce, dashi, mirin and shichimi in a pan and heat through.
Serve the dipping sauce in dishes and garnish with green onions. If using the daikon, simply shred with a grater and balance atop the tofu. Dip the tofu in the sauce and enjoy.
This dish is best prepared in a traditional earthenware nabe pot (donabe).
The dipping sauce is optional. If you want to enjoy real simplicity, just serve the yudofu into individual bowls, garnish with spring onions.