Easily one of the best Indian restaurants I've been to, Utsav is located between 46th and 47th Street, just west of 6th Avenue. The elegant dining room is suspended between buildings, so that you get a nice view of both 46th and 47th as you eat. It's a bit pricey (i.e. it's a special-occasions kind of place), but it's well worth the quality. Just watch out: when they say a dish is spicy, they really mean it!