I don't know why, but I have been hankering a vegetarian version of phở bò lately. There's a phở place across the street from work and the soup looks good, but there's no vegetarian option, so I haven't been able to try it, so I've downloaded a bunch of recipes and now need to figure out what would make a good faux phở.
The biggest problem is that phở bò is built around a carefully constructed beef broth; getting something vegetarian that will replace effectively is going to be a pain. I’m thinking some sort of roasted vegetable broth, but I don't want the veggies to overwhelm things. For my French onion soup, I use mushroom broth, but that definitely changes the taste of things (in a way that I like, but not in a way I want to emulate for phở).
A lesser problem is the nước mắm; I think I've seen a vegetarian version of fish sauce (nước mắm chay) at one of the Asian groceries near work, and if not I can use soy sauce — it's not the same, but it'll work.
I did find a recipe for Phở Bắc Chay, which should be vegetarian, but it's in Vietnamese and my Vietnamese-English/English-Vietnamese dictionary is old and apparently missing quite a few words.... Working with ⓥdict.com, it looks like it does use straw mushrooms (nấm rơm tươi), but Evelin really dislikes their texture, so I think I'll try something else.