Partially cover
To partially cover is to set the lid ajar on a pot so some steam escapes. It keeps a simmer steady and lets the liquid reduce slowly without boiling over.
Also called Partly cover, Lid ajar, Set the lid askew.
"Partially cover" means put the lid on the pot but leave a gap, so some steam can get out. It sits between cooking covered, which traps all the steam, and uncovered, which lets it all escape. Recipes ask for it for soups, stews, beans, tomato sauce and stock that should simmer for a long time.
How to do it
- Bring the liquid to a boil with the lid on, if the recipe says, then lower the heat to a simmer.
- Set the lid on the pot slightly off center, leaving a gap of about 2 to 3 cm (1 inch) at one side.
- Or rest a wooden spoon across the top of the pot and put the lid on top of it.
- Check every 15 to 20 minutes. Adjust the gap or the heat to keep a gentle simmer.
Why it works
A full lid holds in steam and heat. The pot gets hotter and the liquid can boil over, even on low heat. No lid lets steam leave freely, so the pot cools a little and the liquid reduces fast. A partial cover gives you some of each. The pot stays at a steady simmer, the liquid reduces slowly, and the top of the food does not dry out.
How to use it
- Covered: to keep liquid in, as for rice, steaming and braising.
- Partially covered: long simmers where you want slow reduction, such as stock, bean pots, ragù and soups.
- Uncovered: to reduce fast, as for pan sauces and syrups, or when the recipe wants things to thicken quickly.
Common mistakes
- Closing the lid all the way on a starchy liquid such as pasta or beans. It foams up and boils over.
- Leaving too wide a gap. The liquid reduces too far and food sticks or burns. Add hot water if it gets low.
- Forgetting to check. Simmer speed changes as the liquid level drops.
In recipes
"Simmer, partially covered, for 2 hours" is a typical stock or soup instruction. "With the lid ajar" or "set the lid askew" mean the same thing.
Related terms
- SimmerA simmer is liquid kept just below boiling, with small, gentle bubbles rising to the surface. It cooks soups, stews and sauces without toughening them.
- ReduceTo reduce is to simmer or boil a liquid uncovered so water evaporates, leaving a smaller amount that is thicker and more intense in flavor.
- Bring to a boilTo bring to a boil is to heat a liquid until large bubbles rise and break across the whole surface. Here is how to tell, and why recipes then turn it down.
- BraiseBraising browns meat, then cooks it slowly, covered, in a small amount of liquid until tough cuts turn tender and the liquid becomes a rich sauce.
- StockpotA stockpot is a large, tall pot with two handles for stock, soup, pasta and boiling big batches. Here is what size to get and how to use it well.