2 places – neither of which are in Tustin, but they’re close.
(1) Orange Hill Restaurant. Its just north of Tustin Ranch on Chapman. You’ve probably seen it before – it sits on top of a hill with a great view of Orange County. Their brunch is great – so many choices. Not cheap, and it gets crowded by 9am, but its worth it!
(2) Not close to Tustin, and they don’t have a brunch – but the locals in Aliso Viejo “swear” that its the best pancacke house in the County. “The Original Pancake House” is just south of La Paz on Moulton (Irvine Center Dr.). Simply the best pancakes around.