Heat oil in a saucepan over medium heat. Cook the onion, celery, pancetta and garlic, stirring, for 6 minutes or until soft. Add the sweet potato. Cook, stirring, for 1 minute or until combined.
Add the stock, lentils and tomato. Increase heat to medium-high and bring to the boil. Reduce heat to medium-low. Simmer, partially covered, for 15-20 minutes or until sweet potato is tender. Add broccoli. Simmer for 3-4 minutes or until broccoli is tender crisp. Serve and garnish with chopped parsley.