There are two places where a restaurant like the Grand Tier could exist: inside a snowglobe, or inside New York City’s Metropolitan Opera. Luckily, it has been housed in the latter — encased in some 45,000 feet of glass, no less — for the past 60 years, where it offers hungry opera-goers a surreal experience. I have never before, for example, eaten a crab cake while locking eyes with a flying goat...