In a bowl, marinate the diced chicken with soy sauce, rice vinegar, and cornstarch for about 15-20 minutes.
Heat vegetable oil in a large skillet or wok over medium-high heat.
Add dried red chilies and stir-fry for about 30 seconds until fragrant.
Add the marinated chicken to the skillet and cook until browned and cooked through, about 5-7 minutes.
Remove the chicken from the skillet and set aside.
In the same skillet, add bell pepper, onion, garlic, and ginger, stir-frying for 2-3 minutes until vegetables are tender.
Return the chicken to the skillet, add hoisin sauce, sesame oil, and peanuts, stirring well to combine.
Season with salt and pepper to taste.
Garnish with chopped green onions before serving. Serve hot over steamed rice or noodles.