Peel two medium-sized onions, and remove the hearts, cut them in slices (the hearts), and put them with a tablespoonful of butter in a saucepan on a brisk fire, and brown them well. Moisten with a cupful of lean broth, season with a pinch of salt and half a pinch of pepper, cook, and let the sauce reduce for about ten minutes. When ready to serve, cut eight hard-boiled eggs into slices, mix them in the preparation, and let heat together without boiling for two minutes; finish with a teaspoonful of diluted mustard, and then serve.