plastic wrap. And we frequently use the rubber bands from bunches of asparagus or broccoli to keep parchment paper or plastic wrap snug over the top of a bowl. Then there's our own Kathryn, who uses a label maker to keep her leftovers organized (photo below). Is there anything new on the market that we're missing? An alternative to plastic that someone has discovered?
Related: How Can I Re-Heat Without a Microwave? (Images: Elizabeth Passarella; Kathryn Hill)