I'm struggling to think of any. The one in Freo that used to be Miss Maud's wasn't there last we went. There is a very small place in Kardinya that fails your 'moderately good', in that it is exclusively vegetarian (with lots of soy substitute stuff). There is an Indian restaurant in Melville (or one of the close suburbs) that does a nice buffet, and I think that there was a reasonable amount of vegetarian stuff, but we have mostly eaten a la carte there (and I find that Indian is a good option, as there are usually a variety of vegetarian meals on the standard menu).

However, I don't really know anything more convenient to you.