1. In a dutch oven, or heavy pan, cook the onion, carrots, celery and green pepper in the butter for about 8 minutes, or until soft. Add the kielbasa and cook for another 5 minutes.
2. Add the diced potatoes and cook for 2 minutes, stirring, then pour in the stock and water. Bring to the boil, add salt and pepper. Reduce the heat, cover and simmer until the potatoes are soft, about 15 minutes.
3. Meanwhile, make the dumplings: Sift the flour and salt and rub in the butter. Stir in the parsely. Add the egg to the flour mixture and mix to a soft dough.
4. When the potatoes are almost done, drop half-teaspoonfuls of the dough into the simmering soup. Cover and simmer gently for 10 more minutes.
5. Serve soup sprinkled with fresh parsely and bread on the side.