In a small bowl, whisk together brown sugar, soy sauce, hoisin sauce, rice vinegar, minced garlic, sesame oil, red pepper flakes, cornstarch, and cold water until smooth. Set aside.

Cut chicken thighs into 1.5-inch pieces and coat them in cornstarch, ensuring an even coating for crispiness. Set aside.

Heat vegetable oil in a large skillet over medium-high heat. Add coated chicken pieces in small batches and fry for 5-7 minutes, turning until golden and crispy. Remove and drain on paper towels.

Drain excess oil, leaving about one tablespoon. Sauté fresh ginger slices for 30 seconds, then pour in the sauce mixture. Bring to a gentle boil and stir until thickened, about 2-3 minutes.

Return fried chicken to the skillet, tossing in the sauce until evenly coated.

Garnish with green onions and sesame seeds. Serve immediately over steamed jasmine rice or alongside stir-fried vegetables.