Clean the chicken. Put in a saucepan with hierbabuena and water to cover, and simmer until tender, about 25 minutes. Transfer to a chopping board and cut in dices. Strain and reserve the stock.
Heat the vegetable oil in a saucepan over medium heat. Sauté the onion and garlic until medium brown, add ají amarillo paste, cumin, turmeric, salt and pepper. Cook for 5 minutes, then add the chicken and 4 cups of the reserved stock and the diced potatoes and green peas, if using. Add half the chopped hierbabuena. Simmer for 15 minutes or until the potatoes are tender. Garnish with the remaining hierbabuena.
Taste for seasoning, turn off the heat and serve with white fluffy rice.
Recipe by PERU DELIGHTS at https://perudelights.com/chicken-cau-cau/