Season the chicken with salt and pepper. Heat the oil in a large skillet. Add the chicken and brown evenly. Transfer the chicken to a platter. Add the onions, bell peppers and carrots. Cook, stirring, until the onions are soft and translucent. Return the chicken to the skillet and pour in the bouillon mixture. Add the cumin, oregano, and more salt and pepper to taste. Bring the mixture to a boil, then reduce the heat and simmer as long as you can (at least 1 1/2 hours for pieces with bones, about 30 minutes for boneless pieces.) Chicken should be done by then, but cook longer if you can stand the wait. Serve over rice.