The classic egg cream recipe: Whole milk, seltzer and Fox's U-bet syrup. Everyone agrees on that, but when you start introducing sour cream or sarsaparilla, it can become so much more complicated.

About two dozen onlookers watched as OddFellows Ice Cream, Brooklyn Seltzer Boys, Court Street Grocers and Baz Bagels prepared two egg creams each -- modern and classic -- during Sunday's first-ever egg cream competition. The time-honored drink, famously associated with being Jewish in Brooklyn, can be somewhat harder to find these days.

"It's very rare to find these days," said Cecile Tiamsic, 35, who grew up in Manhattan and remembered getting egg creams as a kid. "I remember egg creams and ice cream floats, but you can't find those anymore."

Alex Gomberg, owner of Brooklyn Seltzer Boys, said the trick to making a perfect egg cream is actually in the seltzer, which has to be bottled in the right old-fashioned, siphon-bottle in order to get the right pressure.

Gomberg, who won the contest at The Workmen's Circle "Taste of Jewish Culture" street fair Sunday, said he feels obligated to keep the tradition of making egg creams going.

"It feels awesome to see that people are appreciating the importance of an egg cream," Gomberg said, surveying the line that had formed by his tent after he won.

Ed Levine, a food critic and the founder of Serious Eats, said if you grew up in NYC, or around people from the city, you grew up with egg creams.

"It's important to preserve all traditions in this city where the traditions are being moved out in a profoundly big way," said Levine, who was one of the judges of the competition. "The bottom line is there are a lot of bad egg creams in New York, and it's nice to see in these contestants that there are people who take egg cream-making seriously."

Jake Dell, who owns Katz's Delicatessen and also judged the competition, said he serves a lot of egg creams in the 100-year-old New York establishment. Dell said yesterday's unique takes on the egg cream (like using cherry and vanilla syrup), can help keep the tradition alive, but you can't forget the traditional preparation.

"It's just reinventing in a lot of ways," Dell said. "It's all about the classic at the end of the day. That's largely what I do for a living, I think, is try to keep the classic alive and make sure that people know the classic."

Samantha Stone, 19, brought her boyfriend, Ryan Ogando, 25, to try his first-ever egg cream Sunday. The couple, from Riverdale, split the classic confection from Brooklyn Seltzer Boys.

"They're sweet, I'm a chocolate fan," Stone said. "They're the way they're supposed to taste."