Blot the chicken dry, trim off excess fat, and cut it into 1-2 inch pieces.
Set aside ⅓ cup of the orange juice. In a bowl, combine the orange zest, remaining orange juice, lemon juice, ginger, garlic, soy sauce, and Sriracha.
Heat the vegetable oil in a large skillet over medium-high heat. Add the chicken, salt, and pepper and sear for 4 to 5 minutes, stirring once or twice, until lightly browned.
Pour in the reserved ⅓ cup orange juice to deglaze, scraping the bottom of the pan clean.
Add the orange sauce mixture, stir to coat, and bring to a gentle simmer.
Reduce the heat to medium-low, cover, and simmer 10 to 12 minutes, until the thickest piece of chicken reaches 165°F (74°C).
Uncover, stir in the brown sugar, and raise the heat to medium. Let the sauce bubble for 5 to 6 minutes, stirring a few times, until it reduces and darkens slightly.
Stir the cornstarch and water into a smooth slurry, loosening it with a few drops more water if needed. Stir it into the sauce a little at a time and cook 1 to 2 minutes until glossy and thick; you may not need all of it. Remove from the heat.
Taste and add more salt or hot sauce if desired. Serve over steamed rice or noodles with scallions, sesame seeds, and a side of greens.