Scatter shavings of fresh parmesan over the salad.
Halve the tomatoes and scatter over a large plate. Finely chop the red onion and tear up the mint leaves. Throw the onion and mint over the tomatoes. Can be kept, covered, 3-4 hours ahead. Just before serving, drizzle with extra virgin olive oil, season with salt and ground black pepper and finely grate a little lemon zest over the top.