The Butler and the Chef is the only authentic French bistro in San Francisco.
http://www.butlerandthechef.com/
My favorite brunch spot on the Ballpark side of SOMA! The quiche and croque monsieur/madames are great if you want something more filling. Otherwise, the buckwheat crepes are equally delicious and are a tad healthier.
The best thing to have is the salmon eggs benedict, the bread is amazing.
Be prepared for a long wait. Must order are the quiches, waffles and benedicts!