Slice the bocconcini into quarters and place in a large bowl with the tomatoes.
Mix all the dressing ingredients and pour over the tomatoes and bocconcini.
Steam the broccoli for 7-10 minutes until just cooked (stems should be firm but easily pierced by a knife) and place into a bowl with ice water to cool down. Drain well and add to the tomatoes and bocconcini.
Allow to marinade for 20 minutes up to 3 hours.
Serve at room temperature.