Besh-leth-trill sandwich was a type of sandwich served at Dex's Diner on the planet Coruscant. It consisted of crispy nuna bacon, revwien lettuce and topatos all on either toasted of therm-zapped Pseudograin bread and cost 6.7 credits.
Behind the scenes
Besh-leth-trill is aurebesh for B-L-T.
Sources
Dining at Dex's on Hyperspace (article) (content removed from StarWars.com and unavailable)
