Cut Chicken into 1" cubes, making each piece as uniform as possible.
Place the chicken in a bowl and add salt and sherry. Stir to combine.
In a small bowl, beat the egg white until the gel breaks.
Add the beaten egg white to the chicken and sprinkle in the cornstarch. Mix well.
Finally, add the tablespoon of oil and refrigerate the chicken for at least 30 minutes to allow the coating to adhere.
Velveting in Water
Bring 1 quart of water to a boil in a medium pot and add 1 tablespoon of oil to the boiling water.
Reduce the heat to maintain a gentle simmer.
Add the chicken to the pot and stir gently to separate the pieces.
Stir until the coating turns white, approximately 35-45 seconds.
Immediately pour the chicken into a strainer to drain. The chicken will still be pink inside, as it will finish cooking during the stir-fry.
Velveting in Oil
Heat a wok or skillet over high heat until very hot.
Reduce the heat to medium and add 2 cups of oil. Heat the oil for about 40 seconds until warm but not too hot.
Give the coated chicken a quick and gentle stir, then add the chicken pieces to the hot oil. Stir to separate the chicken pieces and ensure they are evenly coated with the oil.
Lower the heat if the chicken starts sizzling too much.
When the chicken turns white, which takes around 30 to 45 seconds, immediately pour both the chicken and oil into a strainer, reserving the oil.