Indian Restaurant in Paris 2005

Whilst having an evening meal in an Indian Restaurant in Paris, I was quite aware that French was probably the second language of the Indian staff. This left me thinking that English was probably a distant third language ... if I was lucky! The menu had all the items listed in the mandatory French, but also included a faint grey English translation in tiny lettering. Therefore, I was able to avoid escargot and grenoiulle(?).
Because of the extremely limited vocabulary of the restauranteurs, I was on the receiving end of statements such as, "You eat. You sit." I knew they weren't being rude as they were obviously trying to communicate with the ignorant foreigner (me!).

This leads me to a question:

If cows are considered sacred animals in India, why can we buy Beef Vindaloo at an Indian restaurant?