Place chicken pieces in a re-sealable plastic bag and pour buttermilk; stir to mix and refrigerate for 3 hours. Drain well and transfer chicken into a bowl. Add garlic, ginger, black pepper, and salt; marinate for 30 minutes, stirring occasionally.
In a heavy bottom pan, pour about 1-inch oil and heat it up until it reaches 350ºF. Meantime, in a large skillet over medium-high heat, combine Shoaxing wine, rice wine vinegar, soy sauce, gochujang, honey, brown sugar, sesame oil, garlic, ginger, and freshly ground black pepper; bring to a boil then reduce to medium-low and simmer for 5 minutes or until the sauce thickens slightly.
Meanwhile, transfer chicken onto a plate and sprinkle corn starch over chicken pieces coating well. Working in batches, drop chicken pieces one at a time and cook for 4 minutes or until golden brown and cooked through. Using a spider strainer, remove chicken pieces and place on a wire rack (otherwise soggy) sitting on a baking sheet lined with paper towel.
Place fried chicken in sauce and quickly toss to coat well. DON’T let them sit too long otherwise they will get soggy and not crispy anymore. Serve them over a bed of rice and garnish with peanuts and green onions.