This Southwestern and Tex-Mex chain with the cowboy motifs serves quick orders.. In Short So why the success? Maybe it's the black bean cheese quesadilla samples by the door. Or the smoky grilled tomato queso. Or the "patented cheeseburger taco culinary extravaganza." Poster-size menus hang from the ceiling near the central order station, creating a fast-food vibe. Grilled veggie tacos are popular and carnivores can devour a bleu cheese bacon burger.