Slice chicken breast or thigh into uniform, thin pieces, about 1/4-inch thick. This helps with even tenderizing and cooking.

In a medium bowl, add the sliced chicken and sprinkle with baking soda. Mix thoroughly with your hands, ensuring every piece of chicken is coated. Let it sit at room temperature for 10-15 minutes. Do not exceed 15 minutes, as over-marinating can affect texture.

After 10-15 minutes, transfer the chicken to a colander and rinse it very thoroughly under cold running water for several minutes. Use your hands to separate the pieces and ensure all baking soda is washed off. This is crucial to prevent any soapy taste.

Pat the rinsed chicken pieces very dry with paper towels. Excess moisture will prevent the marinade from adhering properly.

Return the dried chicken to the clean bowl. Add cornstarch, soy sauce, rice wine (if using), water, and sesame oil (if using). Mix well until all chicken pieces are evenly coated.

Allow the chicken to marinate for at least 15 minutes, or up to 30 minutes, before cooking. It can also be refrigerated for up to an hour, but for best results, use it fresh.

When ready to cook, add the velveted chicken to your stir-fry recipe. For exceptionally tender results, you can quickly blanch the chicken in boiling water for 30-60 seconds or briefly shallow-fry it in hot oil until it just turns opaque before adding it to the main stir-fry sauce and vegetables.