In a mixing bowl, combine soy sauce, rice vinegar, minced garlic, grated ginger, and sugar to create a flavorful marinade. Cut the boneless chicken thighs into bite-sized pieces and add them to the bowl, ensuring all the chicken is well coated. Let the chicken marinate for at least 30 minutes to absorb the savory flavors.

While the chicken marinates, mix the all-purpose flour, cornstarch, salt, pepper, and baking powder in a separate bowl. This dry mixture will create a crispy coating for the chicken.

Heat oil in a deep skillet or frying pan to 350°F (175°C). Using tongs, dredge each piece of marinated chicken in the flour mixture, ensuring an even coating. Fry the chicken in batches for 6-8 minutes or until golden brown, crispy, and cooked through.

In a new bowl, whisk together gochujang, honey, soy sauce, sesame oil, and rice vinegar to create a sticky, flavorful sauce. Adjust the sweetness and spice levels according to your preference.

Prepare a steamer and bring the water to a gentle boil. Place the bao buns in the steamer basket, making sure they don't touch each other. Steam the buns for about 5 minutes until they are soft, warm, and fluffy.

To create your Korean Fried Chicken Bao Buns, generously brush the crispy chicken with the prepared gochujang sauce. Carefully place the sauced chicken inside the steamed bao buns. Top with sliced scallions and any additional garnishes.