At the restaurant, how can you recognize a real recipe at ABTM?

The best way is to ask to see the original bottle, which should be opened and in use in the kitchen.

 Since dishes made with TBVM are certainly more expensive than others, the absence of the original bottle is a clear indication of dishonesty, as only the certified product contained in the officially authorised bottle can be called Traditional Balsamic Vinegar of Modena P.D.O.