Scrub and trim the beetroot and put them in a foil-lined roasting tin with the cumin seeds and vinegar and bake in a preheated oven, 190°C (375°F), Gas Mark 5, for 30 minutes or until cooked. Check by piercing one with a knife. Allow the beetroot to cool slightly and then, wearing food-handling gloves, rub off the skin and slice the globes into halves, or quarters if large.
Meanwhile, peel and segment the oranges. Make the dressing by whisking the honey, mustard, vinegar and oil. Season to taste with salt and pepper.
Put the watercress in a bowl with the beetroot and add the dressing. Mix gently to combine. Arrange the oranges on a plate, top with the salad and crumble over the cheese. Season with cracked black pepper and serve.