Place diced chicken in a bowl and cover with cold water. Add 1 teaspoon of baking soda, mix, and let the chicken sit in the brine for at least 15 minutes, or up to 1 hour.
Drain the water off the chicken and use a paper towel to pat dry, then add the chicken back to your bowl. Sprinkle the cornstarch over the chicken and mix using tongs. Add the soy sauce, egg white, and black pepper and toss again until combined and the cornstarch mixture resembles a paste.
Heat a large skillet over medium high heat and add the avocado oil. Add the chicken to the hot pan leaving space between each piece of chicken—you might need to cook your chicken in two batches. Cook for 3-4 minutes until the chicken is golden brown on the pan side. Use the tongs to flip the chicken and cook again until lightly golden brown, then sear on a third side if necessary so all sides are crispy. Transfer chicken to a paper towel lined plate.
If you have any excess oil in your pan, soak it up with a paper towel, but don't wipe the pan. In a small bowl add the soy sauce, brown sugar, orange zest, orange juice, grated garlic, grated ginger, rice wine vinegar, sesame oil, and cornstarch. Whisk together until the cornstarch is dissolved, then add to the pan.
Cook over medium heat until the orange sauce comes to a boil. Add the chicken, toss, in the orange sauce, then remove from heat. Serve immediately over prepared rice. Enjoy!