In a medium bowl, whisk together chicken broth, fresh lemon juice, rice vinegar, Shaoxing wine (if using), sugar, cornstarch, lemon zest, and a pinch of salt. Set aside.

In a large bowl, combine bite-sized pieces of boneless chicken breast with vegetable oil and a sprinkle of salt. Marinate for about 15 minutes.

Crack an egg into the bowl with the chicken and mix gently. Add cornstarch and stir until the chicken is coated evenly.

Heat vegetable oil in a large skillet over medium-high heat. Cook the chicken in a single layer until golden brown, about 2-3 minutes per side.

Transfer the chicken to a plate lined with paper towels and let cool for 2-3 minutes.

In the same skillet, sauté chopped green onions and ginger for 1-2 minutes until fragrant.

Pour the sauce into the skillet, cooking until it thickens and becomes glossy, about 2-3 minutes.

Return the crispy chicken to the skillet, tossing until well-coated. Cook for an additional minute before serving.