Heat the olive oil in a large saucepan, over medium heat. Sauté the onion and garlic until softened, about 3 minutes. Stir in the water, chicken broth, cabbage and carrots and bring to a boil. Reduce the heat to low and simmer until the vegetables are tender, about 30 minutes. Transfer the soup to a food processor or blender and process. Return the soup to the pan and re-heat. Serve topped with thyme.