Remove the roots and very dark green part of the leeks. Cut them in 5 cm. lengths. Wash and drain them.

Melt half the butter in a saucepan and add the leeks. Add a glass of broth and cook for 20 minutes on a very low heat. Put aside.

In another saucepan, partially cook the meat in the rest of the butter, then add the chopped onions and cook for 2 minutes stirring constantly. Add salt, the rest of the broth and cook for 30 minutes.

At the end of 30 minutes, add the leeks and stir. Cover and cook for 40 minutes more.