• 275 g skinless chicken breast fillets, cut into chunks
• 2 sprigs of tarragon, finely chopped
• juice and finely grated zest of 1 lemon
• sea salt and freshly ground black pepper
• 1 egg white
• 2 × 400 g tins chicken consommé or clear homemade chicken stock
• 300 ml water
• a bunch of watercress

Using a food processor, blitz the chicken until you have a fine mince. Put the chicken into a mixing bowl with the tarragon and lemon zest. Season well and beat in the egg white using a wooden spoon. With wet hands, form the mixture into about 20 very small balls.

Empty the consommé into a large saucepan and add the water. Using a fine sieve, strain in the lemon juice. Bring the liquid to a rapid boil, then drop in the chicken balls and leave to cook for 4–5 minutes.

Meanwhile, pick the leaves off the watercress stems. Discard the stems and stir the watercress leaves into the soup at the last moment. Immediately remove the pan from the heat and serve.