Tex-Mex may be one of the Lone Star State's greatest contributions to American dining. Just ask anyone who's moved out of state: A side of queso is not the same delicious bowl of liquid cheese in other parts of the country.

But where did this offshoot of Mexican cuisine originate? Many credit Dallas-born chain El Fenix.

On Sept. 15, 1918, local entrepreneur Mike Martinez opened the first El Fenix -- and 98 years later, it's still one of the benchmarks for Tex-Mex cuisine. Now that calls for a toast.

El Fenix marks its 98th anniversary this Thursday, and to celebrate, the location in downtown Dallas is offering 98-cent cheese enchilada plates to dine-in guests.

In an environment where restaurants are often here today, gone tomorrow, the chain offers a great example of how times have changed. In 1937, for example, El Fenix's enchiladas cost a mere 40 cents, according to The Dallas Morning News. El Fenix was a family-owned operation until 2008 when Martinez sold it to Firebird Restaurant Group. It now boasts 23 locations in the region, including one at the WinStar World Casino in Oklahoma.

Diners should expect to wait in line on Thursday for the food special. But if that's not your thing, El Fenix is also offering a coupon for a $5.98 enchilada plate, which is valid at all its restaurants Sept. 15-25. (Download here.) And if that doesn't fill you up, the restaurant is running a contest for free El Fenix for a year. Register before Sept. 25.

The fine print

El Fenix's 98-cent enchilada deal is available exclusively at the flagship restaurant in downtown Dallas. The plate includes two cheese enchiladas topped with chili con carne and served with rice and beans. Limit one order per guest and no substitutions allowed. Offer is valid all day.

El Fenix is located at 1601 McKinney Ave., Dallas. It will be open Thursday from 11 a.m. to 9:30 p.m.