Wash and thinly slice the celery.
Cut the turkey breast into strips.
Pat the beetroots dry, then quarter and cut into slices. (Wear rubber gloves to avoid staining your hands.)
Whisk together the vinegar, oil, stock and mustard. Season with salt and pepper.
Mix the beetroot, celery and turkey breast with the dressing and season with salt and pepper. Cut the bread into slices and serve with the salad.