Banquet pot pies sickened thousands with salmonella in 2007. The corporate parent, ConAgra Foods, and others have decided to leave the “kill step” to eliminate pathogens up to the consumer’s cooking at home.

The frozen pot pies that sickened an estimated 15,000 people with salmonella in 2007 left federal inspectors mystified. At first they suspected the turkey. Then they considered the peas, carrots and potatoes.

The pie maker, ConAgra Foods, began spot-checking the vegetables for pathogens, but could not find the culprit. It also tried cooking the vegetables at high temperatures, a strategy the industry calls a “kill step,” to wipe out any lingering microbes. But the vegetables turned to mush in the process.