Now make the dressing. In a bowl whisk together the sugar, mustard, salt, pepper and walnut oil until well blended. Add the cider vinegar and whisk again. Cover and leave in fridge until needed.
Meanwhile cut each cheese in half and grill under a fairly high heat , cut side up, until melting and just golden. Arrange on the salad leaves.
Add the walnuts and sage to the dressing at the last minute and drizzle over the salad to serve.