The three main versions of this saying that a Google search finds are "There's a pork chop in every beer," "There's a sandwich in every beer," and "There's a steak in every beer." None of them appear to be very old sayings. Here's the rundown on each one.
'a pork chop in every beer'
A posting from September 23, 2000, at StraightDope.com titled "The New and Improved Signature Thread," which collects "favorite signatures on the board," lists as one of them "There's a pork chop in every beer."
An October 2, 2002, question at the message board of the same site asks whether a (12-ounce, presumably) beer has the same nutritional value as a pork chop, a question that suggests why someone thought of equating beer and pork chops in the first place. (One answer the the Straight Dope query made the seemingly sensible observation that, although the total calories from the two items might be roughly equal,the pork chop's calories come from protein and fat, while the beer's come from carbohydrates and alcohol.)
The 2000 match is the earliest one that my Google search could find.
'a sandwich in every beer'
The earliest Google match for this phrase is an October 9, 2003, comment on Fark.com, which says simply "There's a sandwich in every beer."
However, a Google Books search finds an instance from Robert Seidenberg, "Menace to Propriety," in Ski magazine (December 1995):
4:10 Last run of the day. "In every beer there's a sandwich," philosophizes Crane. "And I'm hungry. It's time for the 'Menace to Sobriety' part of the equation."
'a steak in every beer'
This expression, which appears to be especially common in Australia, has an earliest Google search occurrence of February 17, 2002, at the Bodybuilding.com forums, where a poster says "No way. They say there's a steak in every beer. More beer I say"
It seems highly likely that one of these three expressions supplied the inspiration for the other two, but the earliest recorded instances I've been able to find for each variant are fairly closely bunched: "sandwich," December 1995; "pork chop," September 2000: and "steak," February 2002. I suppose that "There's a sandwich in every beer" is the current top contender, but a periodicals archive for the 1970s through the 1990s might contain older instances of every one of these expressions.