In a large bowl, mix together the flour, garlic powder, onion powder, salt, black pepper, paprika, and baking powder.
In another bowl, pour the buttermilk over the chicken pieces, ensuring they are well-coated. Let them marinate for at least 30 minutes in the refrigerator.
Heat about 2 inches of vegetable oil in a deep skillet or pot over medium-high heat until it reaches 350°F.
Remove the chicken from the buttermilk, allowing excess to drip off, then dredge each piece in the flour mixture, ensuring they are fully coated.
Carefully place the coated chicken in the hot oil, frying in batches to avoid overcrowding. Fry for about 8-10 minutes or until golden brown and cooked through. Use a meat thermometer to ensure the internal temperature reaches 165°F.
While the chicken is frying, prepare the sauce by combining gochujang, honey, soy sauce, rice vinegar, sesame oil, minced garlic, and grated ginger in a saucepan. Heat over medium heat until simmering, stirring occasionally. Cook for about 5 minutes until slightly thickened.
Once the chicken is cooked, remove it from the oil and drain on paper towels.
Toss the fried chicken in the sauce until well-coated.
Serve hot, garnished with sesame seeds and sliced green onions.