Slice each pear into 8 pieces, remove the core and plunge into water with a dash of lemon juice in it to stop them from browning.
In a bowl, combine the sugar and soy sauce and stir until the sugar has dissolved. Add 2 handfuls of walnuts to the bowl and stir to coat thoroughly.
Lay the walnuts on a baking tray and place in the oven at 130 degrees Celsius for 8 to 10 minutes to dry out. Keep and eye on them you want them to have just started to blacken but not too much. They go very bitter when blackened. Allow to cool.
To serve, arrange the watercress on a plate, top with the sliced pear then the crumbled Roquefort and finally scatter over the walnuts. The pears are so juicy you don’t need any other dressing.