My favourite is currently one from a stand here in Paris that first puts a ton of cheese on the round thingies that are used to do crepes and then places the sausages on top of the cheese. HE then proceeds to fry everything there. After it's done, he rolls the cheese around the sausages (the cheese is half-crispy half melting) and then puts in in a fresh made half-baguette with ketchup and the fabulous french mustard (from Dijon).
Delicious.