1. Boil potatoes, drain and mash. Add butter, seasonings and cheese. Beat and form into potato cakes. Fry until brown.
2. In a heavy skillet slowly fry the onionin 1 tablespoon fat until tender and lightly browned. Add tomatoes. Season and stir until bubbling and thickened. Place some of the tomato mixture on each potato cake and set a poached egg on top.