Before assembling your salad, pat the beetroot dry on kitchen paper, or your salad with turn pink. Divide the potatoes, mozzarella, tomatoes, courgette and beetroot between 4 plates, then make your dressing.
To make your dressing, simply whizz up the oil, vinegar and herbs together and season with black pepper. You can also do this with a fork or whisk, but I have a mini food processor that is perfect for these small jobs.
Dress the salad and serve. You may season with salt if you think it needs it.