I say that tongue in cheek, but I was pleasantly surprised when I discovered I could continue picking lettuces and other Winter veggies well past the frost date. Lettuce has a chemical that prevents frost damage and it recovers nicely from being frozen. I discovered one morning, snapping off a couple frozen leaves for that day's sandwich, that it is best not to pick lettuce leaves when frozen as they will be quite wilty. If you wait until they are thawed they will be crisp and delicious.
And they come back fast during an Indian summer too! I now have had two lettuce patches this fall. One patch gave out after weeks of supplying us lettuce, and I had to plant another one. Not yet big enough to pick yet, but I dare say I will have lots of lettuce in two more weeks.