Bring a large pot of water to a boil over high heat. Fill a large bowl with ice water.
Trim the broccoli into florets. When the water boils, add the florets and a big pinch of salt. Cook until the broccoli is just tender, about 3 minutes. Drain and plunge the florets into the ice water to stop the cooking. When they are thoroughly chilled, drain, and spread them out onto a paper towel lined sheet pan to dry.
In a small bowl, mix together the yogurt, cream cheese, and onion soup mix. Transfer the yogurt mixture to a large resealable plastic bag. Arrange the broccoli, on a serving platter, cut sides down, so that they form a domed pie-like appearance. Cut the tip off the corner of the bag and pipe a lattice-work design over the broccoli. Garnish with the cherry tomatoes and serve.