Cut your tomatoes into bit sized pieces, I tend to cut cherry ones in half and larger ones into 4-6 pieces - place in a large bowl.

(If you are adding sun-dried tomatoes add them now too)

Next add the finely chopped red onion together with a sprinkling of salt and plenty of freshly ground black pepper

Next add the Olive oil and pesto and stir round

Add the torn Mozzarella and torn Basil leaves and just combine using  2 spoons , you don't want it all slimy and green so just minimal mixing

Make it look pretty with a few basil leaves on top