DO-AHEAD TIP: Cook turkey.
In a small bowl or cup, combine orange juice, water, sherry (if using) and crushed red pepper flakes; add chopped turkey then set aside.
Heat the oil in a large skillet over medium-high heat; add bell pepper strips, snow peas, and gingerroot; stir-fry for 2 to 3 minutes. Drain chopped turkey, reserving marinade.
Add cornstarch to marinade and blend well.
Add turkey and marinade to the skillet; cook, stirring constantly until thickened.
Serve on a bed of fresh spinach or mixed salad greens. Garnish with chopped Italian parsley.