Downtown Dallas destination restaurant El Fenix began celebrating its 100th birthday in January. Today, we learned the year-long fête includes the potential for free food -- $100 worth of it, to be exact -- with an arty twist.

The restaurant chain unveiled Wednesday a new mural on the side of its flagship location at 1601 McKinney Ave. Guests are encouraged to take a selfie in front of it and share the photo on social media with the hashtag #DontMessWithTexMex. Each month, one winner will be chosen to receive a $100 El Fenix gift card through the end of 2018. 

Boasting a bright Texas flag set against a sky blue background, the mural includes the words "Don't Mess With Tex-Mex" in massive, bold lettering. 

It's a rallying call with a storied history. 

El Fenix, celebrating 100 years, will debut new margarita made with our favorite hipster mixer

Dallas Morning News business columnist Cheryl Hall detailed in January how locals issued the phrase amid concerns that the flagship building was purchased by its current owner -- Firebird Restaurant Group -- in 2008 as a property play due to its prime location near the American Airlines Center in Victory Park and the House of Blues in the historic West End. 

Firebird CEO Mike Karns said the group has "embraced the heritage," and he hopes the centennial celebration will prove it, Hall reported. 

Over the years, the restaurant has hosted rock stars and dignitaries from Mick Jagger (who was once mistaken for a cab driver) to Mayor Mike Rawlings, who, after saving a choking customer in 2015, is honored with his own day every year on Aug. 8. 

Here's more from Hall on the restaurant's fascinating history. Take your own selfie at this location.

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