In a large bowl, combine flour, cornstarch, salt, sugar, and water and mix well. Add chicken pieces and mix until evenly coated.

In a deep pot, heat oil over a medium flame to 350 to 375 degrees Fahrenheit (if you don’t have a thermometer, this should take about five minutes—when you drop in a piece of chicken and bubbles form around it, the oil is ready). Drop chicken pieces in a few at a time, and fry until they turn golden brown and float to the top, about three to four minutes. With a slotted spoon, remove chicken and drain on paper towel.

In a large pot, bring sauce ingredients to a boil. Lower flame and add chicken. Toss until evenly coated. Transfer to a bowl and sprinkle sesame seeds on top. Serve over rice.