How to keep avocados green: There's nothing wrong with a bit of brown on the fleshy part of a halved avocado (just scoop that browned part off!), but we have a trick for keeping them on the green side as long as possible. Right after you cut whichever half (or third or fourth) of the avocado you're not going to use, place it flesh side down in a bowl of water. Add a bit of lemon juice to the bowl, then refrigerate it. The avocado should stay relatively green for at least a few days.
Michelle Stark, Times food editor