The tale of 'Imbianchimento' and the curious Spider Treviso

This weekend involved a trip to Borough with a good friend, where along with bumping into the brilliant chef Peter Gordon (one of my chef heros), I came across this rather magnificent specimen, the Spider Treviso. Of Italian origin, it is of the Radicchio family with it's winey red, bitter leaves.
First cultivated by the ancient Egyptians and then Italian monks in the 1400s who had to vary their sparse vegetarian diets, this curious plant has gone through quite a transformation over the years. The Belgian agronomist Francesco Van den Borre, already famous for applying techniques to endive to whiten the leaves, set to work on these radicchio that grew in the Treviso region.
The Imbianchimento process involves a lot of work, with the plants harvested in the autumn, trimmed, and packed into wire baskets. These are then placed in darkened sheds for a few days, with their roots bathed in circulating springwater. This bathing process and light deprivation makes the leaves take on the deep purple pigment, which when deeper in colour means the more bitter the taste, which makes these leaves so prized as a leaf by gourmets around the world.
With my history lesson in mind, I figured these would make the most delicious winter salad with one of my other favourite ingredients, pear.
This makes a fabulous starter or an end to a meal where a cheese course would take precedence. The beautiful leaves are made glossy with walnut oil, and combined with the pear (that I poached in a mulled wine - orange peel, caraway seeds, cloves, cinnamon and cardomon until soft and juicy), which once mulled adds additional purple to the dish. Over this crumble some delicious Scottish blue cheese (mine was from Neal's Yard Diary) and roughly chopped walnuts. This was finished with a quick vinagrette of 3 parts walnut oil to 1 part of the cooled mulled wine, salt, pepper and a final grating of orange zest to lift all of the flavours.