Place the chicken cubes in a mixing bowl. In a separate small bowl, whisk soy sauce and cornstarch until smooth. Stir in brown sugar, rice vinegar, and sesame oil until everything is well blended.

Scoop out 2 tablespoons of this sauce and pour it over the chicken. Toss to coat evenly, then set it aside to marinate for 15 minutes.

To the remaining sauce, add a splash of water and stir until smooth. Set this aside for later.

Heat a large skillet or wok over medium-high heat. Once hot, drizzle in a little oil and add the bell peppers. Stir-fry for 3 to 5 minutes until they begin to soften.

Stir in the garlic and ginger and cook for another 1 to 2 minutes, just until fragrant. Transfer the vegetables to a clean bowl and set aside.

In the same skillet, add more oil if needed. Add the marinated chicken and cook, stirring occasionally, for about 4 to 5 minutes or until fully cooked.

Stir in the peanuts and dried red chilies, cooking for an additional minute to toast them slightly. Keep stirring so they don’t burn.

Return the cooked veggies to the skillet, pour in the reserved sauce, and sprinkle with red pepper flakes. Stir well to coat everything.

Lower the heat and simmer gently for 3 to 4 minutes, until the sauce thickens to your liking.

Top with sliced green onions and enjoy hot over a plate of steamed white rice.