Preheat the oven to 200°C (400°F). Wrap the beetroots in aluminum foil and place them on a baking tray. Roast for 30-40 minutes until tender.

In a small bowl, whisk together olive oil, balsamic vinegar, honey, salt, and black pepper.

Once the beetroots are cool enough to handle, peel and slice them. In a large mixing bowl, combine arugula, sliced beetroot, crumbled feta, and chopped walnuts. Drizzle with dressing and toss gently to combine.