Die besten Restaurants mit Modernes indisches-restaurant Essen in Frankfurt am Main

They told my friend who was there as a tourist and only speaks English NONE of the dishes have nuts. Shortly afterwards they slapped him with a card which was of course German and said everything that has nuts is in there. HOW SHOULD HE READ THEN IF HE DON'T SPEAK GERMAN?! He had an extremely allergic reaction for a day in a country he was unfamiliar with. If he hadn't stopped eating, he could have ended up in the hospital. What is that please???