How to Thicken Sauce Without Flour

A good sauce can make or break a dish, but it can be tricky to get it just right. It’s not just the flavour you’ll need to consider as the texture and thickness of the sauce are also vital.

Whether it’s a gravy for a stew, pasta sauce or a curry, a thin, watery sauce is a disaster. Your natural instinct may be to add some flour to thicken things up but what do you do if there’s none readily available?

Don’t panic. There are a number of other ways to thicken up a sauce without ruining the overall taste, and there is a great deal of science to back it up.


How to Thicken a Sauce Without Flour or Corn Starch

cooking pasta sauce

Flour and corn starch are the obvious go-to solutions as they can both thicken up a sauce quickly without affecting the flavour.

Corn starch is gluten-free, so is an excellent option if you have someone in the house following a gluten-free diet.

There are other options to thicken up a sauce but some of these may affect the flavour. You’ll need to choose carefully to make sure your thickener complements the recipe. The options include:

  • Tomato paste
  • Pureed vegetables
  • An egg yolk
  • Add some chia seeds
  • A spoonful of butter

All of these can thicken up a sauce in varying degrees. Butter is the least effective but can work if you just need a little help.


Do Onions Thicken Sauces?

sliced Onions

Onions are a natural thickener and when added to a dish can help to thicken a sauce. They should be chopped as finely as possible to thicken the sauce the most effectively.

Of course, onions have a strong flavour profile and won’t be suitable for every dish.

This is one of the options, along with tomato paste, where you’ll need to be very certain that the flavour won’t be adversely affected.

Onions work very well as a thickener in curries or other onion-based dishes.


Will a Sauce Thicken in the Oven?

If you have the option to leave your dish in the oven for longer without ruining the ingredients, this can be one of the simplest ways to thicken the sauce.

The heat from the oven will help excess liquid to evaporate, leaving your sauce naturally thicker.

Once you’ve removed the dish from the oven, if you can wait a while before you serve it up, the sauce may thicken further.

Lots of sauces will thicken as they cool, taking the hard work out of rectifying a sauce that’s too thin!


Does Simmering Thicken a Sauce?

Simmering pasta sauce

If your dish is being cooked on the stovetop, simmering is another way to use the natural properties of heat to remove some of the liquid.

Once again, you will need to be careful not to ruin the carefully balanced flavours and consistency of your other ingredients by using too much heat.

But if it’s possible to simmer your dish for longer, gently bringing it to the boil, a watery sauce will quickly thicken up.

This option works better with the lid off as it allows the condensation and steam to escape, giving a quicker result. This technique is known as a reduction.


Can Cream Thicken a Sauce?

If you have a cream-based sauce, adding double cream can help to thicken it up without altering the flavour profile too much.

Sour cream and yoghurt can also be substituted for double cream if you don’t want to add too much sweetness.

Thickening up a sauce using a cream-based ingredient is possible, but you need to be very careful when heating it up.

Bringing dairy to the boil can cause it to split and curdle, and you could end up with a sauce that’s completely ruined and not just watery.