In a bowl, combine pork, soy sauce, and Chinese cooking wine. Stir until pork is coated and marinate for about 30 minutes. Drain well.
In a bowl, combine flour, cornstarch, and salt, and pepper to taste. Dredge pork in flour mixture to fully coat.
In a pan over medium heat, heat about 2 inches deep of oil. Add pork cubes and cook, turning as needed, for about 6 to 10 minutes or until golden, crisp, and cooked through.
With a slotted spoon, remove pork from the pan and drain on paper towels. Keep warm.
In a pan over medium heat, heat about 1 tablespoon oil. Add onions and bell peppers and cook, stirring regularly, for about 30 seconds or until half done. Remove from pan and drain on paper towels.
In the pan, add sweet and sour sauce mixture, whisking regularly, and bring to a boil. Continue to cook, whisking regularly, for about 2 to 3 minutes or until thickened.
Add onions, bell peppers, and pineapple chunks. Cook for about 30 to 40 seconds or until tender yet crisp.
Add fried pork and quickly toss to coat. Remove from heat and serve immediately.
Alternatively, pan-fry the bell peppers, onions, and pineapple chunks until tender yet crisp. Arrange fried pork cubes on a platter and garnish with the sauteed bell peppers, onions and pineapple chunks. Drizzle with the prepared sweet and sour sauce just before serving.