Jonathan Gold remembers the culinary landscape of Mexican food in Los Angeles when he first began reviewing restaurants in 1984. He describes it as mostly "#2 combo plates," but in the late 1980's he began to see regional specialties appear on menus. He ends his review with John Sedlar's Rivera, calling it "possibly the most ambitious and maybe well realized Mexican restaurant that there's ever been in the United States."
The restaurants Jonathan mentions are Marix, Antonio’s, Border Grill, Rebecca's (now closed) and Rivera.
You can find all of Jonathan's restaurant suggestions on the Good Food restaurant map.