For a fast lunch, or a slow dinner, Edo in Subiaco is great for Japanese food. I've eaten there many, many times and have always had a fantastic meal. The atmosphere is great too - it's got a cafe vibe. Excellent prices too. Edo is just off Rokeby Road, on Barker Road.
I would have to say Mr Munchies in Mt Lawley.
I have only ever had sushi there however they have other things.
Their sushi is fantastic, and so, so different to any other sushi. They have the most amazing things in them, and well worth going, however met a friend there last week, and there was a line to get in at lunch time.
It is not the most comfortable place, and is small and crowded however still well worth it, and I will generally not line up to wait for a cafe/restaurant.