I say Genghis Kahn Mongolian BBQ, it's in chatswood, on top of Andronicus and across the road from Fina. Plenty of parking available
The way the restaurant works is u go and pick which ingredients and sauces u want and the guys cook it for you on a big hot plate. It's around $18.50 for unlimited servings so it's really good value I've been there a few times and never regretted it.
We will need to book early (say Tuesday) so we'll need an idea on numbers faily soon