Soak the wakame and mushrooms in 300ml warm water for 30 minutes.
Lift out the wakame and cut out any thick stalks,
Cook the noodles according to the packet instructions.Drain.
Put the stock in the large saucepan with the remaining ingredients,
except for the miso paste and tofu.
Add the wakame, mushrooms, and socking water.
Bring to the boil, reduce the heat, and simmer for 3 min.
Blend a ladleful of the stock with the miso paste until smooth.
Pour back into the pan and stir gently.
Divide the noodles among 4 large open soup bowls.
Add 2 slices of tofu to each bowl and ladle the very hot soup over.
Serve at once with sweet chili sauce to drizzle over, if using