How to Make It
In a large pot, heat the oil over moderately low heat. Add the onion; cook, stirring occasionally, until translucent, about 5 minutes.
Add the cabbage, potatoes, water, broth, bay leaf, thyme, and salt to the pot. Bring to a boil. Reduce the heat and simmer, partially covered, stirring occasionally, until the cabbage and potatoes are tender, about 20 minutes.
Meanwhile, put a large nonstick frying pan over moderate heat. Add the sausage and cook, stirring occasionally, until browned, 2 to 3 minutes. Remove the sausage from the pan and drain on paper towels. Just before serving, remove the bay leaf from the soup and stir in the sausage.