1. Heat oil in a frying pan and add chicken cubes. Sauté until the chicken changes color. Remove chicken cubes from pan and set aside.
2. Add flour to the pan and stir quickly. Add orange juice, vinegar, and sugar. Cook, stirring, until the mixture thickens.
3. Return the chicken to the pan and cook for a few more minutes. Place on serving platter and garnish with cashews and scallions.