Combine soy sauce, white wine, sherry, cornstarch, garlic, and shredded chicken in a bowl. Mix well and refrigerate for 30 minutes.
Heat 2 tablespoons oil in a large pan over medium-high heat. Add the hot peppers, peppers, and onion. Sauté for 5 minutes, stirring frequently. Remove from pan and set aside.
Remove chicken from marinade, drain well, and reserve the marinade.
Add remaining oil to the pan and heat over high heat until very hot. Add drained chicken and fry for about 2 minutes, stirring constantly. Pour in reserved marinade and tomato paste. Add the sautéed peppers and onion. Simmer for 3-4 minutes until chicken reaches 74 °C (165 °F). Season to taste with salt and pepper.