Whisk brown sugar, soy sauce, rice vinegar, garlic, and ginger in a bowl until brown sugar is completely dissolved. Set aside.
Heat 2 tablespoons of vegetable oil in skillet on medium heat. 30 seconds.
Add the chicken pieces in the pan and pour 1/3 cup of the brown sugar mixture over chicken; cook the chicken until it is no longer pink inside. Depending on the size of chicken pieces, 3-6 minutes a side. Make sure to stir the brown sugar mixture in the skillet so it doesn’t burn.
Remove the cooked chicken pieces from the skillet and set aside. The sauce should remain in the skillet.
Pour in the remaining brown sugar mixture. Cook on high heat, stirring the mixture until reduced and syrupy. This may take 15+ minutes. It’s okay if the brown sugar mixture is at a rapid boil. This is the process of reducing the mixture to a thicker consistency.
Once the brown sugar mixture has reduced and become syrupy, turn the heat down to medium and add back in the chicken pieces. Stir in the red pepper flakes, peanuts, jalapenos and green onion; cook until warmed through, 3-4 minutes.
Pour the chicken and sauce over Jasmin rice and sprinkle with cilantro. Enjoy!!