1) Preheat the oven to 190C/Gas 5.
2) Place all of the large beets on a sheet tray and bake for 40 to 45 minutes or until a fork slides in and out of the beets easily. Add the baby beets to the tray for the last 20 minutes of cooking time. When the beets have cooled, peel them. Slice the large beets into 1-cm thick slices. Cut the baby beets in half.
3) Place the rocket in a bowl, drizzle in about half of the vinegar and olive oil, and season generously with salt. Toss gently to incorporate all of the ingredients. The rocket should taste very flavourful but not soggy. Arrange on four individual salad plates. Add all of the beets to the salad bowl and toss with the remaining oil, vinegar and salt.
Arrange the dressed beets on the rocket and top with the pistachios and shaved Pecorino cheese.