Heat the oil in a large saucepan and saute the onion, leeks, celery, and garlic 5 mins.
Add the carrots, cabbage and potatoes and stir well. Add the herbe. Cover with vegetable stock and simmer, with the lid on, for about 1 hour. Stir occasionally, and add more liquid if necessary.
If you're using fresh tomatoes, sit them on top of the veggies for a minute or two, until their skins peel away easily. Then stir the skinned tomatoes into the soup. If using canned, add to the soup and stir well.
Season with salt and pepper and serve.