For marinade, combine soy sauce, vinegar, and sugar in a large bowl. Stir/whisk until sugar is dissolved.
Cut chicken into large chunks. Place in marinade and set aside for maximum 15 minutes.
Make spice mixture by grinding peppercorns (save 2 tbsp for later) and stirring with salt and sugar
Heat oil to 325F/165C
Make dredge by combining rice flour, cornstarch, and seltzer water
Place chicken into the dredge, shaking off excess, then fry until crispy and lightly browned (5-7 min)
Sprinkle cooked chicken with spice mixture
Heat up 1 tbsp oil in skillet over medium-high heat
When oil is hot, add green onions, whole peppercorns, the red chilies, and a sprinkle of the spice mixture.
Toss until fragrant, then add the chicken pieces and toss for 1-2 mins.
Serve with cilantro as garnish and a side of white rice.
