It is the first time the retailer has manufactured the food it sells.
Forty per cent of the ingredients supplied to the site - dubbed the Fresh & Easy kitchen - are provided by UK suppliers Wild Rocket Foods and 2 Sisters Food Group.
Both companies have invested £100m in setting up processing plants next to the new Tesco site.
“We have lots of experience in this, and the margin is much better,” said John Burry, Fresh & Easy’s chief commercial officer of centralised planning at the new plant. “Why pay someone else to do it?”
The kitchen produces 120 lines, including sandwiches, sushi and ready meals.