In a bowl, mix together all the ingredients except for the bread and cabbage. Don't over-crush the croquette so that you can cut it later.
Spread margarine (separate from the listed amount) lightly over both slices of bread. Put the mixture from Step 1 onto one slice of bread, and shredded cabbage on the other.
Toast in a toaster oven.
Sandwich the two slices of bread together.
Cut in to easy-to-eat pieces and serve.
Story Behind this Recipe
I had leftover croquettes and didn't want to put them in the freezer, so I thought I'd make a sandwich with them. This really is delicious. I highly recommend it.
Generally, you should use a large croquette. If you want crispier cabbage, put it in the sandwich after toasting instead. When cutting the sandwich, if you press the knife evenly down on the surface (rather than sawing), it makes for a more visually appealing cut.