Step 1: In a large bowl, season the chicken winglets with salt and pepper. Add cornstarch and toss until all the winglets are evenly coated.
Step 2: Heat vegetable oil in a deep skillet or pot to about 175°C. Carefully add the winglets in small batches and fry them until they are golden brown and crispy. Remove them from the oil and drain them on a paper towel-lined plate. Repeat until all the winglets are fried.
Step 3: In a separate bowl, whisk together ketchup, rice vinegar, honey, soy sauce, and cornstarch until well combined. Set aside.
Step 4: In a large skillet, heat 1 tablespoon of vegetable oil over medium heat. Add minced garlic, diced bell peppers, and onions. Sauté until they are slightly softened. Pour in the sweet and sour sauce mixture and stir well. Cook for a few minutes until the sauce thickens and becomes glossy.
Step 5: Add pineapple chunks (if desired) and cooked chicken winglets to the skillet. Stir gently to coat the winglets with the sauce. Cook for an additional 2-3 minutes to heat the winglets through.
Step 6: Serve the sweet and sour chicken winglets hot and garnish with some fresh green onions or sesame seeds, if desired. Enjoy them as an appetizer or serve them with some steamed rice and veggies for a complete meal.