Sometimes you finish cooking a stew, casserole or other gravy-based dish like a pie filling, and while you're happy with the flavour, it's still too runny. This happens more often with dishes made in slow cookers as they don't allow water to evaporate.


At this point you have a choice: you can boil off some of the liquid (but this will also concentrate the flavour, which you may not want, and you could overcook the ingredients), or you can add an ingredient that will not affect flavour but simply thicken the liquid for a creamier texture.

The three main thickening agents for gravies are flour, cornflour and arrowroot. The first two are normally used in savoury dishes while arrowroot tends to be used in sweet dishes – that said, arrowroot will work in a savoury dish as it has no flavour. All three contain starch that swells when mixed with liquid and heated.

Using flour as a thickener


Flour can be used in three ways:

1. It can be added to the meat as it's being fried, before liquid is added, and this way it will thicken a stew as it cooks. We use this method in our beef & vegetable casserole recipe.

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2. Flour can be mixed with a little cold water to make what is unattractively called a ‘slurry’, which is then stirred to disperse it and stop it forming clumps – a technique called ‘slaking’. After adding to the stew, it's brought to the boil to cook out the flour taste and allow the starch to swell. Try this using 1 tsp flour at a time, incorporating each lot before adding another.

3. Alternatively, you can mix equal quantities of flour and butter (and/or oil) together to make a paste called ‘beurre manie’. Whisk bits of the resulting paste into the hot stew where they will dissolve and disperse the flour. (This works better if you have lifted the meat or veg out of the gravy or sauce, first.) Use 1 tbsp flour and 1 tbsp butter to start and whisk it in bit by bit, then make more if you need to. Make sure you boil the liquid for a couple of minutes to cook out any raw flour. Use this method in our coq au vin recipe.

Using cornflour as a thickener


Cornflour is an ideal thickener if you're a coeliac or simply intolerant to gluten, because as the name suggests, it is made from corn. Be aware, though, that it produces a slightly more gelatinous texture than flour, so don’t overdo it or you’ll end up with a slightly gloopy sauce. It also works well for healthy cooking as it doesn’t add as many calories to a dish.

Try this in our ultimate makeover: chicken pie recipe.

How to thicken slow cooker stews and casseroles

The nature of slow cookers is that they don’t ever get very hot, so this means that any thickener may not, depending on the model, ever get hot enough for the starch to swell – remember that both flour and cornflour need to be boiled. It may be necessary to transfer the sauce or gravy to a saucepan in order to boil it.

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Do you have a secret ingredient to thicken your stews? Leave a comment below...

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