Combine chicken pieces, vegetable oil, and salt in a big bowl. Mix well and let marinate for 10 to 15 minutes.
Combine all the sauce ingredients in a small bowl.
Add the beaten egg into the bowl with the chicken. Stir to mix well. Add cornstarch. Stir to coat chicken, until it forms an uneven coating with a little dry cornstarch left unattached.
Heat oil in a large nonstick skillet over medium-high heat until hot. Add chicken all at once and spread out into a single layer in the skillet. Separate chicken pieces with a pair of tongs or chopsticks.
Cook without moving the chicken for 2 to 3 minutes, or until the bottom turns golden. Flip to brown the other side and until the inside is just cooked through, 2 to 3 minutes. Transfer chicken to a big plate and remove the pan from the stove. Let cool for 2 to 3 minutes.
Wipe the extra oil from the pan using a few layers of paper towel held in a pair of tongs, leaving about 1 tablespoon of oil in the pan. Add the ginger and green onion. Stir fry a few seconds to release the aroma.
Add the chicken back into the pan and pour in the sauce. Stir to mix well.
Transfer to a plate and serve hot over steamed rice with lime wedges, if needed.