Orange County Christmas diner/brunch
You might want to try contacting The Clubhouse at South Coast Plaza in Costa Mesa. I know they do holiday brunches, but cannot remember if they do one for Christmas...maybe Christmas Eve. But you'll really love their food...I love the Champagne Sunday Brunches there.
You could try contacting Taps in Brea as well. That's my all-time favorite...well, next to the Ritz-Carlton.
Taps Fish House & Brewery
101 E. Imperial Hwy., Brea, CA 92821
3333 Bristol, Costa Mesa, CA