Thicken it

There are different ingredients you can use to thicken a sauce. Wheat flour needs to be mixed with fat to allow it to distribute itself into a liquid. As the fat melts, the flour is spread evenly into the liquid and, as long as it is stirred, no lumps will form. If you add flour directly to a liquid it will immediately form lumps and no amount of whisking will make them disappear. Wheat flour also needs to be boiled to cook it or it will keep its raw flavour.

Cornflour can be added directly to cold liquid (water). It will form a paste and you can then add this to a hot liquid to thicken it. It turns clear when cooked so it is useful in a sauce where you want a translucent finish.