One of the greatest and most economical kitchen timesavers is ready-to-eat prewashed packaged spinach; look for it in the produce department.
A yellow or white onion can be used in place of the red onion.
This salad can be made up to one day in advance. Layer the salad as directed except for the croutons. Cover tightly and refrigerate until serving time. Add the croutons and toss if desired before serving.