Preheat the oven to 200C/Gas 6. Prep the potatoes first by slicing them at 3mm intervals but don't slice all the way through, place onto a baking tray drizzle with oil and season with salt and pepper and chuck in the oven for 40/45 minutes until they begin to open and go golden brown.
Toast the walnuts in a hot dry pan for 1 or 2 minutes and set aside.
Make the dressing - Into a bowl add the mustard, honey and sherry vinegar and whisk until combined, then slowly add the olive oil in a steady stream until the dressing thickens slightly. Crumble the blue cheese over the hot potatoes, sprinkle the walnuts over then drizzle the honey and mustard dressing over the top and serve....