A friend of mine recommended this soup to me, and it really is lovely. The recipe is from BBC Good Food and I just made a couple of little changes. You do need to get a couple of speciality ingredients, Miso paste and Mirin, but these are definitely worth the investment (together they cost me £3.50 from Tesco) as this is such a quick and easy mid-week dinner you will be doing it again and again!
I got my Mirin (a sweet japanese rice wine) from Tesco Here’s the link as well as my miso paste (here). Most of the big supermarkets will do them, but you can also find them on Amazon: Mirin here and Miso paste here.