off limits

off limitsは「立ち入り禁止」という意味で使われます。しかし、実際にどこかの地域に立ち入る時だけではなく、菜食主義者にとっての魚や肉というように「踏み込んではいけない」状況にも使われています。(Minnesota)

http://www.japantoday.com/category/food/view/veggie-sushi-will-win-over-all-your-senses-in-the-end

　　　　　　　　　　　　
TOKYO —
For many vegetarians and vegans, Japan can be a difficult place to get something to eat. Sushi is nearly completely off limits for those who forego meat, and very few Japanese people would consider California rolls real sushi, especially the chef of Vegetable Sushi Potager.
Vegetable Sushi Potager—a restaurant located in the glitzy Roppongi Hills area of Tokyo—is serving up a full course meal based entirely on vegetables. I was told that although its presentation is high quality, like a lot of vegetarian cooking, the deliciousness of it doesn’t hit you over the head right away. It takes time to build bit by bit from the bottom of your heart as you go through each course culminating in a new understanding of the word “delight.” That’s some big praise, so I was understandably skeptical