In a large mixing bowl, combine dark brown sugar, finely ground white pepper, rice flour, salt, minced garlic, soy sauce, vinegar, and unsweetened pineapple juice. Mix until you achieve a uniform marinade. Add the skinless chicken thigh fillets, ensuring they are evenly coated. Cover the bowl with plastic wrap and refrigerate the mixture for at least 1 hour, or up to 3 days for optimal flavor infusion.

Heat a large skillet over medium-high heat and add the marinated chicken along with 1 cup of water. This will help create a steam effect that ensures the chicken cooks through while absorbing the marinade flavors. Allow the mixture to simmer uncovered for about 15-20 minutes, stirring occasionally, until the liquid reduces significantly and coats the chicken.

Once the water has mostly evaporated, drizzle a tablespoon of oil into the skillet. Increase the heat slightly and continue to cook, stirring occasionally. Watch closely as the chicken begins to caramelize—about 5 to 10 minutes will yield a beautiful golden color, contributing to that signature tocino glaze.

After the chicken is caramelized and evenly browned, remove it from the heat. Serve your delicious Chicken Tocino hot, accompanied by garlic rice and a side of spiced vinegar for a traditional Filipino experience.