Place the chicken into a large bowl.

In a small bowl, whisk the soy sauce and cornstarch together until completely dissolved. Add the brown sugar, rice vinegar, and sesame oil. Whisk until well combined. Take 2 tablespoons of the sauce to marinate the chicken breasts. The remaining sauce will be used in the stir fry.

Pour 2 tablespoons of the sauce in the bowl with the chicken. Toss to coat all the pieces. Set aside and let marinate for 15 minutes.

In the bowl with the remaining sauce, add water and stir until well combined. Set aside.

After the chicken has marinated, heat a large skillet over medium-high heat. Once hot, add a little oil and sauté the bell peppers for 3-5 minutes until they begin to soften and reach desired tenderness. Add the garlic and ginger, and saute for an additional 1-2 minutes until fragrant. Transfer to a clean bowl and set aside.

In the same skillet over medium-high heat, add more oil if needed. Then add the chicken breasts and cook through until no longer pink, about 4-5 minutes. Add the peanuts and dried red chilis to skillet and continue to cook for about 1 minute, stirring often so they do not burn.

Return the sautéed vegetables to the skillet, pour the remaining sauce on top, and season with red pepper flakes. Stir to combine. Reduce the heat to low and bring to a gentle simmer until the sauce is thickened, about 3-4 minutes.

Garnish with sliced green onions and serve over white rice. Enjoy!