Prep the chicken: Pat the chicken dry and cut into bite-size pieces. Dry chicken helps the batter cling and crisp better.
Make the sauce: In a small bowl, whisk honey, soy sauce, vinegar, sesame oil, garlic, ginger, and red pepper flakes.
In another small cup, stir together the cornstarch and water to make a slurry. Set both aside.
Mix the dry batter: In a large bowl, whisk cornstarch, flour, baking powder, salt, and pepper.
Add the wet batter ingredients: Lightly beat the egg, then whisk it into the dry mixture with the cold club soda until just combined. A few small lumps are fine.
The batter should be the consistency of heavy cream.
Heat the oil: Pour 1.5 to 2 inches of oil into a heavy pot or deep skillet. Heat to 350–365°F (175–185°C). If you don’t have a thermometer, a drop of batter should sizzle and rise immediately.
Batter the chicken: Add the chicken pieces to the batter and toss to coat well.
Let excess drip off, but don’t wipe it clean—you want a good layer.
Fry in batches: Carefully lower battered chicken into the hot oil, spacing pieces apart. Fry 3–4 minutes per batch, turning as needed, until deeply golden and cooked through. Transfer to a wire rack set over a sheet pan.
Keep the oil near 350°F.
Optional double-fry for extra crunch: After all pieces have had their first fry, raise the oil to about 375°F (190°C) and fry the chicken again for 60–90 seconds. This step keeps the crust crisp even after saucing.
Thicken the sauce: In a clean skillet over medium heat, pour in the honey mixture. Once it starts to simmer, whisk in the cornstarch slurry.
Cook 1–2 minutes until glossy and slightly thick, like warm maple syrup.
Coat the chicken: Add the fried chicken to the sauce and toss to coat evenly. If the sauce gets too thick, splash in a tablespoon of water to loosen it.
Finish and serve: Top with sesame seeds and green onions. Serve hot over rice with steamed broccoli or snap peas.