Cut chicken into bite size (about 1-inch) pieces and place into a large bowl. Add salt, black pepper, milk, and 1/2 cup flour. Mix well until all the chicken pieces are evenly coated in the batter. Let sit for about 10 minutes.

While the chicken rests, combine all the sauce ingredients in a bowl and mix well. Transfer to a saucepan and cook over medium heat until bubbles start to form. Reduce heat to low and simmer for about 1 minute, stirring often, until the sauce thickens slightly.

Add 1 cup of flour to a large zip-top bag. Add the battered chicken, then sprinkle in the remaining 1 cup of flour. Seal the bag and shake until each piece is evenly coated.

Heat a generous amount of neutral oil in a deep pot over medium-high heat. Once the oil is hot (about 350°F / 175°C), carefully add the chicken pieces one at a time. Make sure not to overcrowd the pot (work in batches if needed). Fry each batch for 10–13 minutes, or until golden brown and cooked through.

For extra crispy chicken, remove the chicken pieces from the pot and let them rest for a couple of minutes, then return them to the hot oil for a second fry (about 1-2 minutes).

Remove the chicken from the pot and transfer to a large bowl. Drizzle the prepared sauce over the chicken and toss until evenly coated.

Garnish with chopped green onions or sesame seeds, if desired. Serve warm and enjoy!