Prepare the Oranges:You need to segment the oranges. First you cut a slice from the top and bottom of the orange and then sit it on your board. Take a flexible knife and cut away the skin and pith from the orange - following the curve of the orange will help you make a clean cut. When each orange is free of pit, take a small knife and cut out the segments - you need to leave the membrane behind, all you want is the pure flesh.Do the segmenting over a bowl so to collect the juice as you cut and when all the segments are free, squeeze the remnants in you hand to extract any other juice.Prepare the Radish:Wash the radish well to remove any dirt and then grate the radish.Assemble the salad:Add the grated radish to the orange segments and juice - season with a little salt and pepper and gently toss to combine. Let this sit in the fridge for a few hours before serving.When ready to serve, sprinkle over with a little finely diced walnuts, you could also add some freshly shredded mint if you like.