Slice the celery, carrot and onion about 5 mm thick. Julienne the bell peppers and ginger thinly. Cut the cabbage roughly.
If you cut the vegetables too small they will disintegrate. If you want the soup to have volume cut them up into large pieces. I recommend using a large pot to cook the soup.
Put all the cut up vegetables, konbu seaweed, salt and water into a pot and start heating. When it comes to a boil lower the heat to medium, simmer for 20 minutes and it's done.
If you are using a pressure cooker, cook under pressure for 5 minutes, then turn off the heat, and leave to cool down naturally. Season with salt and pepper before serving.
Story Behind this Recipe
When I was eating the "fat-burning soup" that was popular some time ago, I got bored of it and modified it to make it interesting. I reduced the seasonings and ingredients in this recipe so that it can be adapted in many ways.
The key is to just flavor it lightly enough so that you can make variations to it easily later on. Try adding miso, soup stock, chicken stock, tomatoes and so on later on. The soup keeps in the refrigerator for a week, and for about 2 weeks in the freezer. I always store it in one-cup portions in the freezer.