Cut the chicken thighs into bite-sized pieces.
In a wide shallow bowl, mix together flour, cornstarch, a sprinkle of salt, and a sprinkle of black pepper to taste.
In a small deep bowl, whisk together eggs, a sprinkle of salt, and a sprinkle of black pepper to taste.
Dip a few pieces of chicken at a time first in the wet batter, then into the dry mixture, shaking off any excess. Set on a plate and bread all the chicken.
In a pot over medium-high heat, combine soy sauce, orange juice, rice vinegar, brown sugar, sesame oil, minced garlic, minced ginger, and red pepper flakes. Bring to a simmer, then add the cornstarch slurry (water and cornstarch whisked together) to thicken into a glaze. Once thickened, remove from heat and transfer to a large bowl. Set aside.
Heat vegetable oil to 350°F in a frying pan. Fry the breaded chicken in two batches, ensuring not to overcrowd the pan. Fry until golden, about 4 minutes, then drain on a paper towel.
Toss the fried chicken in the glaze.
Garnish with green onions and sesame seeds, and serve with rice or noodles!