VELVET THE CHICKEN: in a bowl add 1 tablespoon water, baking soda, ½ teaspoon kosher salt, granulated sugar, white pepper, sesame oil, and 1 tablespoon soy sauce. Stir well with a spoon until the baking soda dissolves. Add the chicken and let sit for 10-15 minutes. Then add the rice flour to the same bowl and stir to coat all of the chicken.
FRY: Add 2-3 tablespoons of oil to a deep skillet. Add ⅓-½ of the chicken and cook on one side undisturbed for 2-3 minutes before flipping and cooking the other side for another 2-4 minutes. When the chicken is cooked, remove it to a plate. Add more oil as needed, and cook off the rest of the chicken.
SAUCE: In a bowl, combine the remaining 3 tablespoons of soy sauce, with brown sugar, rice vinegar, and ¼ cup water; set aside.
SAUTE: With 1 tablespoon of oil remaining in the pan, cook the onions and half of the jalapeños and stir to combine. Cook for 2 minutes, then add the garlic for 30 seconds. Pour in the prepared sauce and stir to mix.
FINISH: When the sauce is simmering, add the chicken back to the pan along with the remaining jalapeños, and toss it together. Serve immediately with fluffy rice.