How about a person who knows to order raita for their nan? (They're well-travelled enough to know some basic Indian foods.) Or they're British: our history has been closely entwined with India and the sub-continent for the last couple of centuries. One result of that is that we have a huge number of Indian restaurants, especially in England. Roast lamb is considered a classic English meat - Sunday dinner without a roast is unthinkable. The taste for roast lamb, though, came back to Britain with the Crusaders: it's Middle Eastern in origin. Food reveals history. (And that Sunday dinner without a roast? Not really unthinkable - in fact, it's getting harder and harder to find. Be careful of using food as shorthand. You may be aiming for a 'telling detail' but you'll often end up with a stereotype.)