Peel, halve and core the pear and slice into 8 pieces. Heat the butter in a frying pan and add the pear pieces. Add the vinegar, honey and a grind of black pepper. Fry for 10 minutes until golden. Remove from the heat.
To make the dressing, whisk the vinegar, oil, mustard and some seasoning. Set aside.
Divide the watercress between two plates. Top with the pear, walnuts, cheese and dressing, to serve.