Beef Liver Creole

1 pound beef liver
Flour
3 tablespoons hot butter or drippings
1 1/4 cups sliced onions
1 1/2 cups canned tomatoes
1/2 cup diced celery
1 thinly-sliced green bell pepper
1/2 teaspoon salt
Few grains cayenne
Flour

Cut beef liver into thin slices and dust slices lightly with flour. Melt butter or drippings, then brown the liver. Add onions, tomatoes, celery, green bell pepper, salt and cayenne. Cover the pan and simmer for about 20 minutes. Drain, then thicken the liquid with flour. Add the liver and vegetables. Simmer 2 minutes longer.