Combine corn syrup, vinegar, cornstarch, soy sauce, and ginger; mix well. Set aside.
Trim off large leaves of broccoli; remove tough ends of lower stalks. Wash broccoli thoroughly. Cut off flowerets; set aside. Cut stalks into 1/4 inch slices; set aside.
Heat electric wok or skillet to 325° 2 to 3 minutes. Pour oil around top of preheated wok or edges of skillet, coating sides; allow to heat 1 minute. Add broccoli stems, carrot strips and onion wedges; stir-fry 2 minutes or until vegetables are crisp-tender. Add broccoli flowerets and water chestnuts; stir-fry 1 minute or until crisp-tender. Pour soy sauce mixture over vegetables, stirring well. Cook 1 to 2 minutes or until sauce is thickened. Sprinkle with cashews. Serve immediately.