Peel the beets (wear disposable glovers to prevent it from staining your hands) and place in a large pot. Cover with water and add the sugar, vinegar and a large pinch of salt. Bring to a boil and simmer for 35-45 minutes, until tender. Drain and let cool.
Cook the buckwheat in 300 ml(approximately 1 1/4 cups) of water over medium heat for about 10 minutes. Remove from heat and let cool.
Coarsely chop the hazelnuts and toast in a dry skillet until golden brown. Rinse the arugula and spin dry. Cut the Manchego into thin slices. Rinse the apples, cut in half, remove the core and slice thinly. Cut the cooled beets into slices.