In a large bowl, mix the flour, garlic powder, onion powder, salt, black pepper, and baking powder. Set aside.
In another bowl, pour the buttermilk over the chicken pieces, ensuring they are well coated. Let them marinate for at least 30 minutes.
Heat about 2 inches of vegetable oil in a deep pot or fryer to 350°F (175°C).
Remove the chicken from the buttermilk, allowing excess to drip off, then dredge each piece in the flour mixture, pressing lightly to adhere.
Fry the chicken in batches for about 10-12 minutes or until golden brown and cooked through, reaching an internal temperature of 165°F (74°C). Drain on paper towels.
In a small saucepan, combine gochujang, honey, soy sauce, rice vinegar, sesame oil, minced garlic, and minced ginger. Heat over medium heat until the sauce is well combined and slightly thickened, about 5 minutes.
Toss the fried chicken in the sauce until well coated.
Serve immediately, garnished with sesame seeds and chopped green onions.