Danny Teran’s first business in New York was the Bongo Brothers, a food truck he operated with his brother Albert. After several years, they moved on to another truck, Miami Food Machine. Now photos of the trucks hang in Millie’s, Danny’s new brick-and-mortar spot. When it opens Monday, it’ll offer Cubanos, chimi-chicken sandwiches, yucca fries, empanadas, and cafe con leche, made with salt and butter.