Mooli ke patte and palak combined together also taste quite similar to sarson ka saag. Another time, I had got some mooli (whose leaves were already seperated at the store itself) grated it, squeezed some of its juice, and added to palak and that tasted quite similar too. This occured to me when I was searching for fresh saag and couldn’t find it anywhere in summer…and then I remembered what I studied in my Botany classes during college - that both sarson and mooli belong to the same “Brassicaceae” family. 