Steps
1. Cut chicken into small cubes. Marinate with soy sauce, cornstarch, and a pinch of salt.
2. Heat oil in a pan, stir-fry chicken until cooked. Remove from pan.
3. In the same pan, add more oil and sauté garlic, ginger, and red pepper flakes.
4. Add peanuts, bell pepper, and onion. Stir-fry until vegetables are tender.
5. Mix in chicken, hoisin sauce, vinegar, and sugar. Cook for another minute.
6. Adjust seasoning with salt and pepper. Serve hot.