To Make the Dashi

1. Place the water, kombu, tomato puree, soy sauce, and shiitake mushrooms into a large saucepan and place over medium heat. Bring to a boil and then reduce heat to low – allow to simmer for 5 minutes.
2. After 5 minutes, use tongs to remove the kombu (you can discard it or allow it to dry out and reuse).
3. Open the tin of tomatoes and pour it through a sieve, catching the tomato juice in a bowl below. Keep the tomato juice for another recipe. Roughly chop the tomatoes and place them in the dashi. Allow simmering for another 15 minutes.
4. After 15 minutes, pour the dashi through a fine-mesh sieve (fine enough to catch any tomato seeds). You should now have a slightly rusty coloured, translucent dashi. Return the strained dashi to the saucepan and bring back to a simmer.

To Make the Soup

1. Add the finely sliced runner beans to the dashi and allow it to simmer for 5 minutes.
2. Once the runner beans are tender but not over-cooked, turn off the heat. In a medium bowl, place the miso paste and cover with a ladle-full of the dashi. Whisk well until the miso paste is completely dissolved with no lumps. Pour the miso/dashi mixture back into the saucepan of dashi and whisk well to combine.
3. Divide the miso soup between four bowls and top with the sliced tomatoes, herbs, sesame seeds, and a drizzle of the oil on top.
4. Serve hot and enjoy!