The meat industry admits companies sometimes use meat glue to bind pieces of meat that would normally be thrown away into complete steaks.
Lieu is concerned that consumers don't know what they're being served.
"And just from a straightforward honesty consumers right to know, I think it's important that consumers know what they are eating," Lieu said.
In a letter, Lieu asks the USDA's Food Safety and Inspection Service to investigate. He makes these points:
-- Combining "different meat parts from different animals ... makes it far more difficult to trace what caused the food illness"
-- If a glued steak is "not thoroughly cooked ... the inside can still be contaminated and cause sickness to the consumer."
-- And, "there are stories of transglutaminase causing allergic or other reactions in unwary consumers."
He believes a glued steak ought to come with a label, even at a restaurant.
"I think some consumers are being misled that when they think they are having a whole steak, that it was a whole steak, instead of different parts of different animals being combined together," Lieu said.
This brought immediate response across the industry -- the USDA has approved meat glue. Wednesday, they asked for more time to form a response to Lieu's letter. But added, "USDA is committed to food safety and ... ensuring products ... are appropriately labeled."
The American Meat Institute called on Lieu to stop using "a derogatory and misleading term liked 'meat glue'" and they "vehemently disagree with his allegations about the product's safety."
And the maker of meat glue wrote, "Ajinomoto stands, along with regulatory authorities, behind the safety of this ingredient."
The FDA also considers meat glue safe when handled properly.