Place the beetroot and seaweed in a lidded pan with the water and salt. Bring to the boil and simmer until just tender - about 25 minutes.
Remove the beetroot and cut into 1 cm cubes, keeping the skin on, unless you really can't bear it.
Place into a soup bowl, add the tofu followed by the spring onion.
Stir a little beetroot broth with the miso paste until smooth. Reheat the beetroot broth until it's hot but not quite boiling. Stir in the miso, then quickly pour over the beetroot before it cools down too much.
It's important that you don't boil miso or add boiling water to it as all its probiotic properties will be destroyed.You can replace the beetroot with other vegetables. Carrots are particularly good, as is cabbage and most other greens.This amount is enough for one person, but would make a starter for two.Use a light vegetable stock instead of water if using a pre-cooked beetroot.Please note: calories and other nutritional information are per serving. They're approximate and will depend on exact ingredients used.