Toss chicken pieces with soy sauce in a bowl and let stand at room temperature while you make the batter and sauce.
Off of heat, whisk cornstarch with lemon juice in a small saucepan until smooth. Place on medium heat, then add sugar, broth and zest. Bring to a boil, then reduce heat and cook a few minutes more until sauce is thick and glossy. Remove from heat.
Heat 2-3 inches of oil in a large Dutch oven over medium heat until it reaches 375ºF. (The sides of the pot should be at least twice the depth of the oil.)
In a medium bowl, whisk together the flour, cornstarch, and baking powder. Add the water, stir gently to combine, then add the chicken and any liquid in the bowl. Stir to evenly coat the chicken.
When oil reaches 375ºF, slide 6-8 chicken pieces in using tongs. Work in 2 batches so that the pieces don't touch.
Cook chicken, turning once, until pieces are deeply golden brown and reach 165º in the centre, 3-4 minutes. Transfer to a paper-towel-lined wire rack and continue with next batch until all chicken is cooked. Just before serving, gently reheat the sauce and pour over the chicken, tossing until coated. Top with green onion to serve.
Notes
Air Fryer Adaptation
If you want to try making this lemon chicken in the air fryer, it won’t be exactly like the deep-fried version, but it’s still tasty! Here’s how:Adjust the Coating:Instead of a batter, use a dry coating with a bit of oil for crispiness:
¼ cup all-purpose flour
2 tbsp cornstarch
2 tbsp vegetable oil
¼ cup panko breadcrumbs
Marinate the Chicken:Mix the chicken pieces with soy sauce and let them sit at room temperature while you prepare the coating.Prepare the Coating:Combine the flour, cornstarch, panko breadcrumbs, and oil in a bowl to make a crumbly mixture. Toss the marinated chicken in this mixture until evenly coated.Cook Until Crispy:Preheat your air fryer to 375ºF. Arrange the coated chicken pieces in the air fryer basket in a single layer, making sure they don’t touch.Cook for 10-12 minutes, shaking the basket halfway through, until the chicken is golden brown and reaches an internal temperature of 165ºF.Finish with Sauce:Reheat the sauce, pour it over the cooked chicken, and toss to coat. Garnish with green onions before serving.