There are some essential cooking methods that rely on heat and moisture to get the job done-namely, steaming and braising. Trying to keep both heat and moisture in? Plan to keep the lid on, as this is the best way to achieve both. In the event that your goal is to keep moisture in-like when your pot of soup, stew, or sauce is already at the right consistency but you want to keep cooking the vegetables and melding the flavors-clap that lid on to keep any more liquid from evaporating. Once you've hit the boiling point, remember to take the lid off-this will prevent the pot from boiling over.
That means that if you're trying to bring something to a simmer or a boil-a pot of water for cooking pasta or blanching vegetables, a batch of soup, or a sauce-put that lid on to save time and energy. Always cover your pot if you're trying to keep the heat in.
