Escargot wontons would get anyone’s attention. But French onion soup nachos seals the deal. Adam Branz, the chef behind Ultreia and Split Lip: An Eat Place, is introducing a new concept at Dewey Beer Co.’s Denver taproom. The Delaware-based brewery has been running Mockery Brewing’s former space in the River North Art District since January. The kitchen, called Cul-de-Sac, will feature what Branz calls “sleazy French street food” served out of a food trailer.