Turn on the Sauté Setting on high and saute the onions. After 3-5 minutes add the beans, crushed tomatoes and potatoes. Stir well and add sugar, salt and pepper and water. Bring to a boil and close the lid. Turn on the Pressure Cook setting on High Pressure, More and Pressure cook for 25 min. Use either the natural or quick release method. Open the lid and stir. Serve hot.