Combine first 6 ingredients in large jar. Cover tightly and shake vigorously. (I usually make the dressing a day or two ahead). I also wash spinach the day before and put in paper towels to drain well. Keep both the dressing and spinach in refrigerator.
A few hours ahead you can combine spinach, strawberries, cheese and walnuts together in bowl. Cover and keep in refrigerator. Right before serving, shake dressing well and pour over salad (I don't use it all) and toss gently.