CHATTER 19 - The Distinguishing Dish

For ethnic cuisine are there particular dishes which mark the excellent chef from the very good, the good and the just plain ordinary?
To some degree I think there are such dishes. I think for Chinese sweet and sour prawns in batter is a good example. To retain any crispness the sauce has to be added only a moment before the dish is served The proportions and size of the accompanying pieces onion, pineapple and peppers and the proportion of them to the prawns is important as is the amount they have been cooked. Getting the sauce right is crucial it has to be not to thin nor to gluggy or gluey, not to sweet nor to sour and, obviously, served at an appropriate temperature.
For a French restaurant perhaps French onion soup is a pretty good test. Every element can be out of proportion or the onion can be over caramelised. There area lot of things that have to be just right. I have had so many bad creme brulees and other custard, so many bad attempts at mousses, failed self saucing cakes I think there is probably a dessert which is a true test of a chef. Can a single dish distinguish a Greek chef, a Lebanese a Japanese or any of the other myriad of cooking styles?