viršla

1. frankfurter; wiener; hot dog sausage
   Deca su za doručak jela viršle sa senfom. — The kids had frankfurters with mustard for breakfast.
   Skuvaj par viršli, brzo je gotovo. — Boil a couple of frankfurters, it's quick.

This is the sausage itself; the sandwich is called hot-dog. The Croatian word for it is hrenovka.