MONROE - She was born and raised in Texas and is of Mexican descent, but Cecelia Cameron has never stepped foot south of the border. Maybe that's why she's emphasizing the idea of "American-Mexican" for her new start-up restaurant, Tia's Mexican Grill, which opened last week on the east side of the Square. "I've never been to Mexico, but I've always loved Mexican food," said Cameron, who operates the business with co-owner Bryan Lang.