Le Passage Obligé is not strictly vegetarian or vegan. It used to be until 2009. They are now vegan/vegetarian-friendly. I started out with a fried onion salad which was very good! After eating part of my salad, I had their wild mushroom roast with blackberry ginger sauce and three vegetable puree. The roast was a bit dry, but the sauce was very good. I burnt my mouth on the puree! It was so hot.
Overall, it was a decent choice of restaurant for vegan options. Their menu is marked "(v)" for vegan and "(vv)" for vegetarian. My onion salad was the only vegan appetizer and there was one other vegan entree. There were no vegan desserts.
I don't know much about vegan things in Paris, but I hope they get more restaurants! With such culinary history, I'm sure they could do wonders in Paris with our lovely friend, the vegetable.
For a complete review, please see my blog here: http://veganmiss.blogspot.com/2010/09/vegan-paris-part-two.html