Slice the pumpkin in half across its widest part and discard the seeds and fibres. Cut the flesh into cubes, removing the skin. You should have about 1 kg (2 lb) pumpkin flesh.
Heat the oil in a large saucepan and fry the onion, garlic and chilli until soft but not coloured. Add the pumpkin and celery and fry gently for 10 minutes. Stir in the carrots, parsnips, tomatoes, tomato purée, paprika, stock and bouquet garni. Bring to the boil, then reduce the heat, cover the pan and simmer for 1–1½ hours until the vegetables are almost tender.
Add the beans and cook for 10 minutes. Season with salt and pepper and garnish with the parsley to serve. Serve with crusty bread or garlic mashed potatoes. This stew improves with reheating.