Wendy's introduces upscale "Black Label" burger. (Creative Commons/Flickr)

Wendy's, one of the biggest fast-food chains in the world, has been working on a new burger called "Black Label," according to a recent tip sent in to GrubGrade.

The "Black Label" hamburgers are rumored to come in two flavors: Bacon Portabella and Spicy Santa Fe, and each cost under five dollars. The Bacon Portabella is a quarter-pound patty with mushroom sauce, Muenster cheese, bacon, tomato and pepper sauce.

The Spicy Santa Fe is also a quarter-pounder with guacamole, pepperjack cheese, mixed greens, tomato, red onion and a cilantro jalapeño lime sauce.

Needless to say, Wendy's is working hard to step it up a notch. With their recently debuted Dave's Hot 'N Juicy in the United States and other new burgers being developed around the world, it seems as if the simple idea of "fast-food" that we used to know is being reinvented. 

Though the release date for the Black Label hamburgers is still unknown, a Wendy's representative commented that the tests on the burgers are still in the "very early stages," according to HuffPost Food.

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