1-Step 1: Marinate the Chicken The secret to tender chicken starts with a good marinade. In a large bowl, combine the cubed chicken breast with the sugar, salt, white pepper, sesame oil, garlic paste, baking soda, and cornstarch listed in the marinade ingredients. Mix everything well to ensure every piece is coated. Sesame oil adds a wonderful depth of flavor. Let this sit for at least 15 to 30 minutes, but you can leave it for up to an hour if you have the time. The baking soda and cornstarch work to tenderize the meat, so it stays soft even after frying.

2-Step 2: Prepare the Sweet and Sour Sauce While the chicken is marinating, you can get the sauce ready. In a medium saucepan, whisk together the ketchup, tomato puree, white vinegar, sugar, water, cornstarch, and salt. Stir the mixture until the cornstarch is completely dissolved to avoid lumps. Place the saucepan over low to medium heat and bring it to a simmer. Keep stirring gently as the sauce heats up; it will begin to thicken. Once it reaches a consistency that coats the back of a spoon, remove it from the heat and let it cool. The sauce will thicken slightly more as it cools.

3-Step 3: Mix the Batter In a separate large bowl, whisk together the plain flour, cornstarch (or potato starch), baking soda, salt, and cold water. Whisk until the batter is smooth and free of lumps. You are looking for a medium thick consistency, similar to pancake batter. If it is too thick, add a splash more water. If it is too thin, sprinkle in a little more flour. Let the batter rest for a few minutes while you prepare the frying station.

4-Step 4: Coat the Chicken Set up your coating station. You will need a plate with the extra ½ cup of cornstarch for coating, the bowl of batter, and a clean rack or tray for the coated chicken. Take a piece of marinated chicken and roll it in the dry cornstarch, making sure it is dusted all over. Shake off any excess powder. Then, dip the chicken into the batter, letting any excess drip off. Place the coated chicken onto the rack. Repeat this process for all the chicken pieces.

5-Step 5: First Fry Pour your vegetable oil into a deep pot or Dutch oven. You want enough oil so the chicken balls can float freely without touching the bottom. Heat the oil to 350°F (180°C). If you do not have a thermometer, you can test the oil by dropping a small bit of batter in; it should sizzle immediately and rise to the surface. Once the oil is hot, carefully add the chicken balls in batches. Do not overcrowd the pan, or the oil temperature will drop too much. Fry them for about 2 to 3 minutes until they are a light golden color. Remove them from the oil and place them on a wire rack or paper towel-lined plate to drain. Let them rest for 4 to 5 minutes.

6-Step 6: Second Fry This is the crucial step for getting that restaurant-style crunch. Reheat the oil back to 350°F (180°C). Once it is hot again, add the chicken balls back into the oil for a second fry. This time, fry them for another 2 to 3 minutes until they are a deep golden brown and very crispy. The double frying technique cooks the chicken through fully and creates a hard shell that stays crisp longer. Drain them again on a wire rack.

7-Final Step: Serve and Enjoy Now that your chicken balls are perfectly crispy, it is time to serve them. You can pour the sauce over the chicken in a large bowl and toss to coat, or you can serve the sauce on the side for dipping. Tossing them in the sauce is the traditional way to eat them, but serving the sauce on the side keeps the chicken crispier for longer if you have leftovers. Garnish with some sesame seeds or chopped green onions if you like.