Meanwhile, marinate the chicken fillet.
Mix everything for the marinade: coriander, basil, curry and salt and mash in a mortar.
Coat the chicken fillet.
Cover and refrigerate.
Peel the onion and cut it into thin half rings. Add a pinch of salt and sugar and 0.5 tsp of apple cider vinegar. If desired, you can pre-scald the onion.