How to loosen a thick sauce

What to use, best first

• More of what the sauce is made of. Stock for a gravy, milk for a béchamel, cream for a cream sauce, wine or stock for a reduction. Nothing is diluted except the thickness.
• Pasta cooking water, for anything going onto pasta. Starchy and salty, and it improves the texture rather than thinning it out.
• The dish's own cooking liquid — braising juices, the water the vegetables were cooked in, the roasting tin juices.
• Stock, which adds body and savouriness as well as volume.
• Cream or butter, which loosens and enriches at once. Butter whisked in off the heat is the classic finish.
• A splash of wine, cider or vermouth, reduced briefly so it does not taste raw.
• Water, which works and dilutes everything. Small amounts, and re-season afterwards.

Doing it

1. Take the pan off the heat first. A thick sauce over direct heat catches in seconds.
2. Warm the liquid if you can, or add it gradually. A slug of cold liquid into a hot emulsion or a cheese sauce is a common way to make it grainy.
3. Add a tablespoon or two at a time and stir it fully in before judging.
4. Return to a low heat and bring it back to temperature. Sauces look thinner hot than they will be on the plate.
5. Taste and re-season. Thinning dilutes the salt and the acid as well as the texture.
6. Stop while it is very slightly thicker than you want, since it will loosen as it warms through.

By kind of sauce

Roux-based

Thins readily with warm milk or stock whisked in gradually. Very forgiving.

Cornflour-thickened

Add liquid, do not add more starch. It will re-thicken slightly on standing.

Reduction

Thin with stock or wine, then simmer briefly to marry it rather than leaving it tasting added.

Cream sauce

Warm cream or milk. Cold liquid into a hot cream sauce risks splitting it.

Cheese sauce

Warm milk only, and off the boil. This is the sauce most likely to go grainy when thinned carelessly.

Custard

Warm milk or cream, off the heat, and never reheated hard.

Tomato sauce

Pasta water, stock or a splash from the tin. Water alone flattens it.

Why it went thick in the first place

• Reduced too far. The commonest cause, and the flavour is concentrated rather than lost.
• Too much thickener. Once cooked out it will not thin back on its own.
• It cooled. Starch-thickened sauces set considerably as they cool. Judge them hot.
• It kept thickening off the heat. Cornflour and arrowroot continue to set for a minute or two after the pan comes off.
• A skin formed. Not thickness at all — whisk it back in, and press cling film onto the surface next time.
• Held warm too long, which reduces it further without anybody watching.

Common questions