Blend the walnuts in a food processor to form fine crumbs.
Coat the chicken slices with Dijon mustard and season with salt and pepper.
Roll the seasoned chicken in the ground walnuts until completely coated.
Fry the chicken in olive oil for 4 minutes per side until cooked and drain on paper.
Chop half of the celery into chunks and the rest into 5cm strips.
Toss the celery strips with olive oil, thyme, salt, and pepper.
Char the celery strips in a smoking hot griddle pan for 2 minutes.
Mix the celery chunks with the remaining salad ingredients in a bowl.
Blend egg yolks, mustard, and vinegar in a food processor.
Slowly incorporate the oils into the mixer until a thick mayonnaise forms.
Combine the mayonnaise with the salad and serve topped with chicken and griddled celery.