Prepare the Sauce:

1. In a bowl, mix together water, white vinegar, Worcestershire sauce, tomato sauce, sugar, and a few drops of red food coloring.
2. Stir well until the sugar is dissolved. Adjust the sweetness and sourness to your taste by adding more sugar or vinegar if needed.

Batter

1. Combine the flour and cornstarch in a large bowl
2. Add the water and whisk until smooth
3. Add the marinated chicken and stir until completely coated
4. Set aside and heat the oil

 Cooking

1. Heat the oil over high heat in a wok or pot until it reaches 180°C/350°F.
2. Add the chicken to the hot oil and fry for 9 minutes, or until almost cooked through and golden brown. Ensure the chicken is submerged in the oil for even cooking.
3. Add the vegetables and pineapple and fry for 1 minute
4. Carefully strain the chicken and vegetables from the oil and set it aside on a plate lined with paper towels to drain any excess oil.
5. Set the leftover oil aside to be used next time you deep-fry. Allow it to cool completely before storing it in a clean, airtight container.
6. Heat a tablespoon of oil into the wok
7. Add the sauce and allow the mixture to come to a simmer
8. Combine the potato starch and water until smooth and add it slowly to the sauce while stirring
9. Continue to heat the sauce for another 1-2 minutes, stirring occasionally, until the sauce has thickened
10. Add the chicken and vegetables to the sauce and toss to combine
11. Serve the sweet and sour chicken hot over cooked rice or noodles, garnish with sesame seeds or green onion if desired