"she had brought him some menudo"

Menudo is a traditional Mexican soup, consisting of boiled tripe in either a clear broth or with a red chilli base, and usually eaten with tortillas. The red variation is usually seen in Chihuahua.

The soup is considered a traditional hangover cure in Mexico, which explains why the woman brings it to the ‘crudo’ Billy.

You can find a Menudo recipe here.