Prepare the Chicken: Pat the chicken thigh pieces dry with a paper towel. In a medium mixing bowl, combine the cornflour, salt, and black pepper. Add the chicken pieces and toss thoroughly until each piece is evenly coated.

Fry the Chicken: Heat the oil in a large frying pan or wok over a medium-high heat. Once the oil is shimmering, carefully add half of the chicken pieces to the pan in a single layer. Be sure not to overcrowd it. Fry for 4-5 minutes on each side, until golden brown and cooked through.

Set Chicken Aside: Remove the cooked chicken from the pan with a slotted spoon and place it on a plate lined with a paper towel to drain any excess oil. Repeat the frying process with the remaining chicken. Once all the chicken is cooked, set it aside.

Start the Sauce: Carefully wipe out any burnt bits from the pan, leaving about a teaspoon of oil. Reduce the heat to medium-low. Add the minced garlic and grated ginger to the pan and sauté for about 30-60 seconds until fragrant, being careful not to let them burn.

Combine Sauce Ingredients: Add the gochujang, honey, soy sauce, rice vinegar, and water to the pan. Stir everything together continuously with a wooden spoon or spatula until the sauce is smooth and well combined.

Thicken the Sauce: Allow the sauce to come to a gentle simmer. Let it bubble away for 2-3 minutes, stirring occasionally, until it has thickened slightly to a syrupy consistency that can coat the back of a spoon. What works best for me is watching for the bubbles to become slow and thick.

Coat the Chicken: Turn off the heat. Add the cooked chicken back into the pan with the sauce. Stir in the toasted sesame oil. Gently toss everything together until every piece of chicken is thoroughly coated in the glossy sauce.

Serve Immediately: Transfer the chicken to a serving dish. Garnish generously with the sliced spring onions and toasted sesame seeds. This dish is best served immediately while the chicken is still warm and the coating is at its best.