Peel the onions and remove the root. Cut in half and then into thin slices.
Peel the carrots and cut into diagonal slices. Trim the radishes and cut into quarters. Wash and pick the tarragon.
Peel the prawns leaving the tail intact. Use the tip of a sharp knife to remove the black digestive tract.
Heat a wok and add a little olive oil. Sear the prawns for 3 minutes and then remove from the pan. Season with fleur de sel and piment d'Espelette.
Add a little more olive oil to the same pan and cook the carrot, onion and radish for 2 minutes. Deglaze the pan with the white wine and reduce the liquid. Add 500ml water, the white balsamic vinegar, cardamom and the star anise. Simmer over a low heat for 10 minutes.
Add the prawns and half of the tarragon leaves and cook over a low heat for a final 5 minutes.
Serve the prawn soup with the remaining tarragon leaves and a pinch of piment d'Espelette.
«If you do not have any piment d'Espelette, feel free to use a little fresh chilli»