Cut the chicken thighs into bite-sized pieces and combine cornstarch, all-purpose flour, salt, and black pepper in a large bowl. Toss chicken pieces to coat and let sit for 10 minutes.

Heat vegetable oil in a skillet over medium-high heat until 350°F (175°C). Fry chicken pieces in batches for 4-5 minutes until golden brown, then drain excess oil.

Discard excess oil, leaving about a tablespoon in the skillet. Sauté minced garlic, ginger, and dried red chilies over medium heat until fragrant, about 30 seconds.

Whisk soy sauce, rice vinegar, sugar, hoisin sauce, cornstarch, and water in a bowl until combined, then set aside.

Pour prepared sauce into skillet with aromatics, bringing to a simmer for 2-3 minutes until thickened.

Add fried chicken back into the skillet and toss to coat. Cook for another 2 minutes to absorb flavors.

Remove from heat and drizzle sesame oil over the dish. Optionally add crushed red pepper flakes, tossing gently to combine.

Serve General Tso Chicken over steamed rice, garnished with sliced green onions.