Sauce thickening can be annoying, frustrating and messy. However there are a range of ways to solve your sauce thickness issues, depending on your dietary requirements, the type of dish and how much time you have to make it happen. I use all 6 of these methods to thicken sauces and my choice tends to depend on what dish I am making and what ingredients I have on hand.

1. Roux

This butter and flour thickening method is commonly used for creamy milk based sauces such as béchamel and also gravies.

To make a thick roux based sauce, use this simple formula and multiply:

Roux Recipe:


1 tablespoon of butter
1 tablespoon of flour to
1 cup of liquid


The butter is melted until bubbling and then the flour is added and stirred through while on heat until it resembles wet sand. Hot or cold liquid can be added at this point and the roux based whisked into the sauce. You can add liquid to the pot or scrape the roux into a hot liquid in another pot. If the liquid is already hot, the thickening happens faster. If the roux is cooked into a cold liquid, you’ll have some simmering and constant whisking to do. Using a roux will make your sauce opaque so this does not suit sauces that should be clear. Whisk the roux thickened sauce on high heat until it begins to boil and allow to boil for 1 minute or until desired texture has been achieved.

2. Starch

Similar to a roux, starches such as corn starch, potato starch, tapioca starch etc. use a similar formula.

For every cup of liquid you want to thicken, combine 1 tablespoon of starch with 1 tablespoon of water and make a slurry before adding to the warm liquid you want to thicken.

The benefit of using starches is that they do not contain gluten and can suit a number of diets, such as gluten free, dairy free, grain free etc. Also these starches cook out clear, so they do not make sauces cloudy. Do not use a starch to thicken acidic sauces, instead use arrowroot as below. Starches are great for thickening dairy based sauces. The benefit of starches is that they work immediate and as you cook out your sauce you will see it thicken immediately. Stir the slurry through continuously until the sauce has reached the desired texture and then remove from heat. Do not use starches if you intend to freeze the sauce.

3. Arrowroot

Arrowroot is what you use when you want to thicken a sauce but it needs to be clear. While gelatine does this, adding meat or fish based gelatine to a sauce can alter the flavour and can have a lot of texture issues. Arrowroot is suitable for vegans and vegetarians and adds no flavour or scent, while gelatine can add a “hoof” sort of taste, which is disgusting. Arrowroot is best for thickening acidic substances while starches are not good for this. Make a slurry with arrowroot powder as above, with a 1 to 1 ratio. Add to warm liquid (it does not need to be hot) and whisk on heat for at least 30 seconds before removing from heat. Use arrowroot if you intend to freeze the sauce.

4. Kudzu powder

While harder to find, this extract of a Japanese vine tuber has alleged health benefits and can be found in health food stores and organic stores. Combine 3 tablespoons of kudzu powder with 3 tablespoons of water to thicken 2 cups of liquid. Kudzu is suitable for vegans, vegetarians and grain free diets, however it should not be used excessively.

5. Egg yolk

This is generally used for thickening custards and dessert sauces, but will also suit creamy savoury sauces also. Use 1 egg yolk to thicken a cup of liquid. The method is pretty specific so follow it carefully.

  • Whisk egg yolk to loosen
  • Add a few tablespoons of hot liquid to the egg yolks and whisk to combine to “temper” the eggs and increase their temperature without turning it into scrambled eggs
  • Add this mixture back into the pot of hot sauce and simmer over medium heat and whisk continuously to combine. Watch as the sauce thickens. Allow to reach boiling point only for a minute or so.

6. Slow Reducing

Finally the slowest and most laborious of all methods, but sometimes it’s the one you have to go with as some sauces need to be reduced and additional ingredients will alter the look and flavour of the sauce too much. Just remember, lid off; the point is for some of the liquid to evaporate in the steam and no go back into the pot. Sometimes simmering seems like it will take forever; if there is nothing actually cooking in the sauce that needs to be reduced, feel free to put it up to full boil and stir it frequently as it boils down. However if there are other ingredients in there, you may want to allow the slow cook to happen lest you destroy the texture of those ingredients.

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