I am looking for a story in which Castiel and Dean are Soulmates. It is a story with soulmate identifying marks / words. 

 Dean has no soulmark. I remember that he has no soulmark/words on his body. Dean has no soulmark because Castiel is mute. Castiel had an accident that made him mute.  

Dean and Castiel meet in the supermarket. And there he shouts the words that Castiel has on his body. This way they find out that they are Soulmates.

In the end they go to a BBQ en tell everybody that they are soulmates.