Preparation

1. In a large saucepan, melt the butter over a medium heat, then add the olive oil.
2. Cook the leeks and carrots until tender (but not browned). Add the flour and cook for 2 minutes, stirring constantly.
3. Pour the chicken stock into the saucepan. Add the potatoes and bring to the boil.
4. Reduce the heat and simmer for 15 minutes, or until the vegetables are tender.
5. Add the sausage, salt, savory and pepper.
6. Leave to simmer for 10 minutes.