Begin by cutting your chicken thighs (hita ng manok) into uniform 1-inch cubes. Ensure your cuts are even for consistent cooking. Place the chicken pieces in a large mixing bowl (malaking mangkok).
In your mixing bowl, combine the chicken with soy sauce (toyo) and Shaoxing wine. If Shaoxing wine isn't available, you may substitute rice wine vinegar or regular white vinegar. Mix well until all pieces are evenly coated. Cover the bowl and place in the refrigerator set at 40°F (4°C). Let the chicken marinate for exactly 30 minutes - no longer, as the soy sauce can make the meat too salty.
While waiting, prepare your cooking station. Set up a wire rack (cooling rack) over a baking sheet, or lay out several layers of paper towels for draining. Have your thermometer ready to monitor oil temperature (temperatura ng mantika).
After 30 minutes, remove the chicken from the refrigerator. Drain off all the marinade and pat the chicken pieces thoroughly dry with paper towels. Patting dry is crucial (importante) for achieving a crispy coating.
In a clean bowl, vigorously whisk two egg whites (puti ng itlog) until they become frothy but not stiff. Add one tablespoon of cornstarch (gawgaw) to the egg whites and whisk until completely smooth with no lumps (walang butil-butil).
Add your dried chicken pieces to the egg white mixture and gently fold until each piece is evenly coated. Allow this coating to rest on the chicken for 5 minutes to ensure proper adhesion.
Pour cooking oil into your deep frying pan or wok (kawali) until it reaches a depth of at least 3 inches. Heat the oil to exactly 350°F (175°C). If you don't have a thermometer, test the oil by dropping a small amount of coating into it - it should bubble gently and float to the surface.
Working in small batches (4-5 pieces at a time), carefully lower the coated chicken pieces into the hot oil. Fry for exactly 3 minutes until they turn light golden in color. Remove them using a slotted spoon or spider strainer (sandok na may butas) and place on your prepared wire rack or paper towels. Repeat with remaining chicken. Let all pieces rest for 5 minutes.
Increase your oil temperature to 375°F (190°C). Return the chicken pieces to the hot oil in batches for their second fry. Cook for 2-3 minutes until they achieve a deep golden brown color. Check that the internal temperature reaches 165°F (74°C) for food safety. Remove and drain again.
In a clean wok or large pan, begin preparing your sauce (sarsa). Over medium heat (350°F/175°C), gently toast your minced garlic (bawang na dinikdik) until fragrant but not brown, about 30 seconds. Immediately add your honey (pulot) and light soy sauce (toyo), stirring constantly to combine.
Let the sauce simmer until it starts bubbling, about 2-3 minutes. Add your calamansi or lime juice (katas ng kalamansi), stirring to incorporate. Reduce the heat to low (200°F/93°C) and continue simmering until the sauce thickens enough to coat the back of a spoon.
Return all your fried chicken pieces to the pan with the sauce. Gently toss everything together for 30 seconds until each piece is evenly coated with the glossy sauce (makintab na sarsa). The sauce should cling to the chicken without making it soggy.
Transfer your honey garlic chicken to a serving plate. Garnish with additional toasted garlic (sinangag na bawang) and chopped green onions (dahon ng sibuyas). Serve immediately while hot, ideally with steaming white rice (mainit na kanin).
For any leftover chicken, allow it to cool completely before storing. Keep the chicken and any extra sauce in separate airtight containers in the refrigerator. When reheating, warm the chicken in an oven at 350°F (175°C) for 10 minutes to restore crispiness, then toss with reheated sauce just before serving.
Note: For best results, maintain your oil temperature (temperatura ng mantika) as consistently as possible throughout the frying process. A thermometer is highly recommended, but if you don't have one, make sure the oil gently bubbles around the chicken - too much bubbling means the oil is too hot, while too little means it's not hot enough.