An elegant and sophisticated salad that makes good use of verjus (verjuice) in the dressing. I use a local blue cheese, such as Roquefort in this salad; however, please do use a local blue cheese of your choice - any creamy or robust blue cheese will marry well with the pears and tart dressing. Verjuice, or verjus, is the juice of unripe grapes. This staple of French provincial cooking, a key ingredient in Dijon mustard, has the tartness of lemon juice and the acidity of vinegar, but the harshness of neither. Its delicate flavour is ideal for everything from stocks to sweet syrups - as long as you know what you're doing. Verjus was also a common ingredient used in English cooking throughout the Middle Ages. I try to make a batch of verjus every year with the green grapes from my non-dessert grape vine - as I love cooking with it. This recipe came from an old copy of Bon Appetit magazine from 2005. Prep time includes the time it takes the pears to cool.