“My favorite animal is steak” is a line that has been credited to American author Fran Lebowitz and reprinted in many books about food and humorous quotations. Lebowitz probably didn’t say the full quotation. She was asked what her favorite animal was, and the book The Portable Curmudgeon (1987) gave her answer—“Favorite animal: steak.”
   
 
Wikipedia: Fran Lebowitz
Frances Ann “Fran” Lebowitz (born October 27, 1950) is an American author. Lebowitz is known for her sardonic social commentary on American life as filtered through her New York sensibilities. Some reviewers have called her a modern-day Dorothy Parker.
 
Google Books
The Portable Curmudgeon
By Jon Winokur
New York, NY: New American Library
1987
Pg. 99:
Favorite animal: steak.
FRAN LEBOWITZ
 
Google News Archive
7 February 1988, The Item (Sumter, SC), “‘Curmudgeon’ is habit forming” by Jeff Danziger (Christian Science Monitor), pg. 10C, col. 2:
For example Fran Lebowitz, who said her favorite animal was “steak.”
(Review of the book The Portable Curmudgeon, edited by John Winokur—ed.)
 
21 December 1989, Park Cities People (Highland Park & University Park, TX)  “Scrooge, Santa trade barbs” by Glenda Vosburgh, pg. 1, col. 3:
“Scrooge doesn’t like kids or animals,” Hardman explains.
 
“In fact his favorite animal is steak.”
(Puppeteer John Hardman—ed.)
 
Google News Archive
23 February 1990, Sunday Star-News (Wilmington, NC),  “Campbell Soup too rich for him” by Malcolm Berko, pg. 4E, col. 4:
My favorite animal is steak, but I must confess that my favorite soup has always been Campbell.
     
Google Books
America’s Food:
What You Don’t Know About What You Eat
By Harvey Blatt
Cambridge, MA: The MIT Press
2008
Pg. 133:
My favorite animal is steak.
—Comedienne Fran Lebowitz
 
Google Books
Meat: A Love Story:
Pasture to Plate, a Search for the Perfect Meal
By Susan Bourette
New York, NY: G. P. Putnam’s Sons
2008
Pg. 186:
I figure that the locals must know a thing or two about a good steak and that few would disagree with Fran Lebowitz, who once declared, “My favorite animal is steak.”
 
Google Books
The 2,548 Wittiest Things Anybody Ever Said
By Robert Byrne
New York, NY: Touchstone (Simon & Schuster)
2012
1,579
My favorite animal is steak. —Fran Lebowitz