We’ve made do with reruns, but Julia Child--who spent most of last year celebrating her 80th birthday--is back on the air with a brand-new PBS show. “Julia Child--Cooking With Master Chefs” premieres this Saturday, locally at noon on KCET. In her show, America’s favorite cook spends time in the kitchen with some of the best young chefs in the country. L.A. chefs to be featured in upcoming segments include Michel Richard of Citrus, Nancy Silverton of Campanile and Mary Sue Milliken and Susan Feniger of City and Border Grill. For this week’s debut, Child travels to New Orleans for a visit with Emeril Lagasse of Emeril’s.