Heat the oil in a saucepan over a high heat. Add the pancetta and cook, stirring, for about 2–3 minutes, or until the fat has rendered and the bacon is golden and crisp. Remove from the pan with a slotted spoon and drain on kitchen paper.
Add the onion and carrots to the pancetta pan and cook for 5 minutes until the onion is softened. Add the celery and garlic and cook for a further 3–4 minutes, stirring occasionally.
Add the thyme, bay leaf, stock and tomatoes, stir and bring to a gentle simmer. Add the lentils and cook for 20–25 minutes, or until they are softened. Remove the bay leaf and use a stick blender or food processor to partially blend the soup, keeping a fairly chunky texture.
Bring the soup back to a simmer, add the cabbage and cook for 3–4 minutes until wilted. Reheat the pancetta in a small frying pan at the same time.
Stir half of the parsley into the soup and ladle into warmed bowls. Serve immediately topped with the pancetta and remaining parsley.
