Peel the plantains and place in a steamer or a saucepan with a rack in the bottom. Add water, leaving the bananas above the level of the water. Add salt and pepper. Bring contents to boiling point; reduce heat and steam bananas until soft.
Lift bananas from the liquid and mash well. Place in top of double saucepan over simmering water until ready to serve with Chicken stew.
To make Chicken stew:
Fry Chicken in hot oil in a heavy sauté pan until brown. Add onions, tomatoes, potatoes, salt, pepper and water. Cover tightly and simmer for about 1 hour, or until Chicken is tender.