Salads are one of summer's perfect meals. You don't have to heat up the kitchen and there's an abundance of fresh vegetables. However, occasionally my lettuce will get a little wilted either because it's so hot out or it's sat in the fridge a little too long while I'm eating other veggies and fruit.
You don't have to toss wilted lettuce though. You can crisp it right back up again by submerging it in a bowl of cold water and a couple of spoonfuls of vinegar (I've had success with both white vinegar and apple cider vinegar) for five to fifteen minutes. Rinse and dry as you normally would and it's like you've got perfectly fresh lettuce again. You can't tell it was ever limp and it doesn't taste at all like vinegar.
It works for me.