Place the prepared chicken into a bowl with the salt and ground black pepper; toss to coat well.
Add the cornstarch and toss until all of the chicken is well coated; set aside until ready to fry the chicken.
In a separate, smaller bowl, add the soy sauce, water, brown sugar and garlic; whisk well to combine; set aside.
Slice the jalapeños into 1/4-inch slices; for a milder taste, remove the seeds from the slices; for a nice kick, leave them in; set those aside until ready to use.
Add four inches of vegetable oil to a heavy bottomed pot; turn on the heat and heat the oil to 315°F.
Once the oil is hot, using tongs, lower the chicken into the oil, one piece at a time; do not overcrowd the pot.
The chicken fries really quickly; it only needs about 5 to 6 minutes, turning at the halfway mark.
Once all of the chicken is fried, increase the heat of the oil to 350°F.
Carefully place all of the chicken back into the oil; this is the second fry and it will add further crisp to the chicken; this process only needs another 3 to 4 minutes.
Remove from the oil and drain well on a wire rack.
In a large skillet, over medium-high heat, add the sauce mixture and bring to a boil.
Once boiling, add all of the fried chicken and the sliced jalapenos.
Toss the chicken well into the sauce and jalapeño mixture.
Continue to move the chicken around the skillet until the sauce has thickened and the water content has evaporated.
Once done, remove from the heat, transfer to a plate and garnish.