Cook orzo in salted water al dente according to package directions.
Drain and rinse with cold water.
Transfer to a large bowl and stir in spinach, feta, onion, pine nuts, basil and white pepper. Refrigerate until serving. Toss with olive oil and balsamic vinegar before serving but not too far ahead of time.
This makes a lot of dressing and you don't have to use all of it if you don't want to.