It's been 27 years since actress Clara Peller angrily exclaimed, "Where's the beef?" in a classic Wendy's commercial. The line comes after she receives a tiny burger on a massive bun (from a financial competitor with the slogan "Home of the Big Bun"). The question has since become a catchphrase for questioning the substance of an idea, a person, or a product.

You've probably heard the question since then – almost certainly in the political arena. But the question as to “where's the beef?” in the fast food context has been raised again. And according to a lawsuit filed in Federal Court, the answer is “apparently not at Taco Bell.”

The lawsuit claims that the fast food chain uses false advertising when it says its Mexican dishes are filled with "ground beef" or "seasoned ground beef," claiming that the “taco meat filling” used by Taco bell is only around 35% beef with additives, fillers, binders, extenders, and preservatives making up the remaining 65%. The suit isn’t looking for money, just truth in advertising

Now according to the USDA website, "ground beef" or "chopped beef" consists of fresh or frozen chopped beef with or without seasoning, shouldn’t contain more than 30% fat, and shouldn’t contain water, phosphates, binders or extenders. The lawsuit claims that Taco Bell's "seasoned beef" contains the prohibited additives backs up their claim citing the restaurant's ingredients list on its own website, which says the "seasoned beef" in, for example, a Beefy Crunch Burrito, contains water, sodium phosphates, soy lecithin, modified corn starch, and anti-caking and anti-dusting agents, among other non-beef ingredients.

Taco Bell President and Chief Concept Officer, Greg Creed, said that the company “is proud of the quality of our beef and identify all the seasoning and spice ingredients” on their website, that they use 100% USDA-inspected beef and simmer it in a blend of seasonings to give it their "signature Taco Bell taste and texture." Oh, and that the final product is 88% ground beef, and the lawyers got their facts wrong.

Taco Bell is trying to set the record straight in a newspaper ad campaign and a YouTube video. But given that consumer expectations regarding healthy, natural ingredients in fast food have increased dramatically over the past decade it raises another couple of questions: What’s in the remaining 12%? And why isn’t the Chihuahua starring in the commercials any more?