First, wash and cut the lamb into larger pieces. Place it in a large pot and cover it with cold, generously salted water, slowly heating until it comes to the boil.Skim off any scum that forms using a slotted spoon.
Chop the onion into small pieces and add it to the meat. Allow the mixture to simmer with a loosely placed lid for about 60 minutes.
In the meantime, chop the carrots and swede into bite-sized pieces, as well as the potatoes. Add the vegetables to the meat and continue to simmer for another 30 minutes.
Finally, taste the soup before serving and season with salt and pepper. You can also add cooked rice or pearl barley if desired.