Unexpected ingredient

I'd been preparing the soup - sautéing the veg - for about 10 minutes before I noticed.


My sons would say it could only happen at our house.
An environmental health officer would close us down.
The cats would say - why not? 


The explanation is that there has been a feline access point through the window behind the gas cooker during recent months for reasons I can't be bothered to detail.


(The mouse didn't make it into the soup which was strictly vegetarian.)