Step 1

Make the sauce: Cook orange zest and juice, soy sauce, sugar, vinegar, stock, and ginger in a medium saucepan over low heat just until bubbling. Whisk in cornstarch. Cook until sauce thickens,  5 to 6 minutes.

Step 2

Make the chicken: Whisk together 2 tablespoons cornstarch and egg whites in a bowl until frothy. Add chicken and let sit, 5 minutes. In a second  bowl, whisk together flour, baking powder, remaining tablespoon cornstarch. Season with salt and pepper.

Step 3

Line a rimmed baking sheet with paper towels. Remove chicken pieces, one at a time (letting excess egg white to drip off), and roll in flour mixture until coated, leave pieces in flour mixture as you work.

Step 4

Heat oil in a wok or large Dutch oven over medium heat until temperature reaches 350°F on an instant read thermometer. Cook chicken, in batches, until golden brown and cooked through, 3 to 4 minutes. Transfer to prepared baking sheet to drain. Season with salt and pepper.

Step 5

Add chicken to sauce and gently toss to coat. Serve garnished with scallions. and rice alongside.