If you're using a big ball of mozzarella, weigh out 50g then cut it into even sized cubes.
Next, make the pesto for the mozzarella. Place the handful of rocket, handful of basil, garlic clove, sea salt and freshly ground black pepper into a blender and blend until smooth.
Mix the mozzarella balls (or diced mozzarella) with the pesto and set aside in the fridge while you prepare the salad.
Cut the tomatoes in half, pick some small basil leaves off the stalks and then mix the 2 together.
Place the rocket and watercress mixed leaves in a bowl or on a plate and spray with some balsamic vinegar.
Arrange the halved tomatoes and basil leaves on top, add the pesto coated mozzarella balls and serve.