How to Make It
In a large saucepan of boiling salted water, cook the orzo until al dente. Drain and cool under running water. Shake out any excess water.
In a large bowl, whisk the vinegar with the mayonnaise. Add the marinating oil from the bocconcini and whisk until smooth. Season with salt and pepper. Stir in the orzo, tomatoes, olives, scallions and bocconcini and let stand for 30 minutes. Just before serving, fold in the spinach and serve.