Opened in 1941, Molina’s Cantina is Houston’s oldest still-operating Tex-Mex restaurant and a venerated institution. The original location at 1919 West Gray was known as Old Monterrey. It was purchased by Raul Molina Sr., who had worked there for a decade, originally as a dishwasher and busboy, and his wife Mary. Today, the business is helmed by the family’s next generation—Raul III, Ricardo, and Roberto. Start off your Tex-Mex feast with staples like the original “Jose’s Dip,” which blends queso with taco meat, and the spicy tortilla soup with chunks…