Cook lentils and sliced onion together until lentils are tender and well dried out, rub through colander, add the browned flour and salt, with water to make of the right consistency. (There should be from 2 1/2 - 3 qts. of soup). Heat 1/2 - 1 hour. This makes an unusually meaty-flavored soup.
The idea of combining onion and browned flour with lentils was given me by one who had spent some years among the French in Switzerland.