For the marinade: Puree the oil, vinegar, chiles and some salt and black pepper in a food processor, then set aside.
For the chicken: Rinse the chicken very well, inside and out, then pat dry and cut off excess fat. Rub the chicken over and under the skin with the chile, soy sauce, ginger, oregano and salt and black pepper, covering all parts. Put the chicken pieces in a resealable bag and add the marinade. Seal the bag and marinate in the refrigerator overnight.
Preheat the oven to 500 degrees F.
Put the marinated chicken pieces into a shallow 13- by 9-inch roasting pan with 1 cup of water and roast for 30 minutes, then tent with foil and roast until browned, about 15 minutes longer.
For the salsa: Meanwhile, mix together the huacatay paste, Huancaina, garlic, rocoto pepper and salt to taste in a blender.
For the salad: Mix together the vinegar, watercress, lime juice and salt and black pepper to taste.
Serve the chicken on a brioche bun with yucca fries, the salsa and watercress salad.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.