Place the red lentils in a bowl and cover with about an inch of water, set aside;
Put the measured water and or Vegetable stock in a large soup pot, with a teaspoon of salt. Bring to boil (skim any scum off that rises to the top) then let it simmer.
In a medium frying pan, saute the onion, carrots, celery and turnip/rutabaga in the olive oil for about 6 or 7 minutes on medium heat. Remove from the heat.
Add the red lentils and the sautéed vegetables, and another teaspoon of salt; stir well and let simmer for about 30-45 min or until lentils are tender.
Season soup with salt to taste and freshly ground pepper.