1. Wash guinea fowl thoroughly, inside and out, put in pot with salt and water and bring to the boil.
2. In the meantime, peel onion and use the clove to spike the bay leaf into it.
3. During the first 30 minutes of cooking time, skim off any scum that forms.
4. At the end of this time, add onion and simmer for 20 minutes until reduced by half.
5. Rinse, dry and cube courgettes (zucchini).
6. Rinse and dry watercress thoroughly and remove any thick stalks.
7. Add chopped courgettes(zucchini) to the stock and cook for 10 minutes.
8. Lift guinea fowl and onions from stock. Allow liquid to simmer, covered, while preparing meat.
9. Take meat from bones, cut into pieces and return to soup.
10. Serve sprinkled with watercress.