Start by cutting the chicken thighs into bite-sized chunks. Season them with salt and black pepper, then toss them in cornstarch until evenly coated. This step ensures they’ll fry up beautifully crispy.
Whisk together the soy sauce, water, brown sugar, and minced garlic in a bowl until well combined. Meanwhile, slice your jalapenos into rings. If you prefer less heat, remove the seeds. Keep these ingredients ready to go.
Heat at least 4 inches of vegetable oil in a deep pot until it reaches 315°F. Gently lower the chicken pieces into the oil without overcrowding the pan. Fry in batches for 5-6 minutes until golden brown, then remove and drain on paper towels. For an ultra-crispy result, increase the oil temperature to 350°F and give the chicken a second fry for 3-4 minutes.
Heat your large skillet over medium-high heat. Add the sauce mixture and bring it to a boil. Once bubbling, toss in the fried chicken and jalapeno slices. Stir everything together until the sauce thickens and coats the chicken. This step is key to infusing every bite with flavor.