I do not understand more than a few words in Mandarin or Cantonese, though my grandmother can read, write and speak both languages. There are no less than three names for this week’s obsession: zhi ma da bing, da bing or Shànghǎi qiāng bǐng, also known as Chinese scallion sesame bread, scallion sesame pancakes or green onion pie. Signature green …