Season the chicken breasts with salt and season with pepper and roast in a frying pan with hot olive oil, then rest a little bit. Cut the peel of the orange and lemons into very fine strips with a peeler (a la julienne) and blanch the peel briefly in boiling hot water.
Cut the celery into tender strips as well, and finely chop the onion. Mix everything together in a baking bowl. Season with lemon and orange juice, add a tiny bit of olive oil and season with salt, pepper and a pinch of sugar.
Finely chop and fold in fresh mint and add the blanched lemon and orange zest. Roughly shred lots of fresh basil over the leaf lettuce.
Cut the chicken breasts in half and arrange on a platter (or cut into small pieces and mix into the leaf lettuce), form the leaf lettuce over the top and spread the feta cheese loosely over the top evenly.
If necessary, drizzle the lettuce with a little extra olive oil.