To Make Barley Salad With Lemon Gravy Ahead of Time - Keep the cooked barley and the lemon gravy mixture separate in air-tight containers up to two days ahead of time. Heat them up separately, then combine them and stir well. At this point, you can add the pomegranate kernels and lemon zest. You want to wait to add these ingredients for optimal freshness and to prevent the pomegranate color from leaching into the barley.