Combine the flour, cornstarch, salt and pepper in a large bowl. Then, whisk in the egg, sparkling water and 1 tablespoon sesame oil until smooth.

Add the chicken pieces to the batter and fold them into the mixture until each piece is evenly coated. Cover the bowl, transfer to the refrigerator and let the chicken soak in the batter for at least 30 minutes.

Next, heat ½ to 1 inch oil to 350°F in a large wok. Working in batches, add a few pieces of the battered chicken to the preheated oil. Cook, turning occasionally, until the chicken is deeply golden on all sides and cooked through. Each batch should take about five to six minutes. Transfer the fried chicken pieces to a paper towel-lined sheet pan to drain excess oil. Repeat with the remaining chicken pieces.

As your last batch of chicken cooks, start the sauce. Warm 1 tablespoon canola oil in a large skillet over medium-high heat. Add the red pepper flakes, garlic and ginger, and cook until fragrant, 30 to 60 seconds.

Add the sugar, brown sugar, rice vinegar, orange juice, soy sauce and orange zest. Stir until the sugars dissolve and the mixture begins to bubble.

Finish the sauce by whisking together 1 tablespoon cornstarch with 1 tablespoon water in a small bowl. Add it to the wok and whisk until smooth. Cook the sauce until it thickens, one to two minutes.

Add the fried chicken to the sauce and gently toss until every inch of the chicken pieces is coated in the sweet and spicy orange sauce. Serve immediately with hot, cooked fluffy rice, and garnish with green onions and sesame seeds if desired.