Fry the bacon. Butter 2 slices of toast on both sides. Fry them until golden brown. Butter the third slice as well, but first cut off the rind and put it aside.
Now put on the sausage, then mozzarella and bacon and a lettuce leaf. Brush it with the mayonnaise. Now place the third slice of unroasted toast on top. Put the cheese on top and brush with the mustard. Put the rest of the vegetables, first the onions, and finally the salad on top and fix with a little butter if necessary. Cut into triangles and serve.
Tip:
Let it stand a little longer at room temperature, it will be really juicy.