In a small bowl, combine all of the sauce ingredients and mix well.
Dice the chicken thighs into approximately 1.5-inch cubes.
Transfer diced chicken into a large mixing bowl and add cornstarch. Toss until evenly coated.
Heat vegetable oil in a large pan over medium-high heat. Fry the coated chicken in small batches until golden brown and crispy, about 6 to 8 minutes.
Remove the fried chicken from the pan and drain on a wire rack or paper towels.
In the same pan, pour in the prepared sauce and simmer for about one minute until it thickens slightly.
Add the fried chicken back into the pan with the sauce and toss until well-coated.
Garnish with orange zest, toasted sesame seeds, and finely chopped green onions before serving.