Alternately, you can cook your food, then chill it in a water bath with ice. Once cold you can freeze it. When ready to eat, you can bring it back to temperature with the Anova or any other alternate method that you like.
I cook my hanger steaks in advance, freeze them. When I want one, I set my Anova, drop the steak in the water, usually, 30 minutes is plenty to bring it back to temperature. I then finish it in a hot pan..
Just write on the rim of the bag what's in it using a Sharpie.