A flat whisk, sometimes called a sauce or roux whisk, is different from the standard whisk in shape and function. Unlike the rounded wire whisk, the flat whisk merely consists of a single set of wires in a U shape, usually about four or five, that all follow a semi-U pattern in different concentric lengths. It isn’t rounded, and is therefore “flat.”
While the rounded whisk is great for mixing and stirring, and for adding extra air to ingredients mixed, the flat whisk is better for mixing sauces in low pans. It’s not spun in the hands like the round whisk, but used to scrape ingredients from one side of the pan to the other. This makes it especially useful when you’re making something like gravy and need to bring together drippings from meat you have just cooked. The scraping action of the whisk helps incorporate these flavorful bits together in order to make delicious gravy.
Many chefs prefer a flat whisk when making sauces that require a roux base (flour and butter). This unusual whisk with its scraping action can keep sauce from collecting or burning on the bottom of the pan. It’s thus useful for Alfredo, Mornay, Béchamel and a variety of other cream sauces.
The flat whisk varies in size and price. Most are between $10-20 US dollars (USD). It’s important to look for one that is sealed where the whisk wires leave the handle. If this part is unsealed, the whisk can be challenging to clean, as flecks of food can accumulate in the center of the whisk and be difficult to remove.
In terms of size, the average flat whisk is about 10 inches (25.4 cm) in length, though a few can be smaller. Since you’re often using this type of whisk to stir over high heat, it helps to find those with a heat resistant handle. You can also find flat whisks made out of nylon that are safe for non-stick pans. Commonly, most flat whisks are made of stainless steel and feature stainless steel, ceramic or wooden handles. A few have a rubberized or nylon coating over the steel handle for better grip.
Though the most common recommendation for the flat whisk is for use in making sauces, the scraping ability of this whisk has other applications. For instance, if you’re trying to get the last bits of batter out of a bowl for a cake, a flat whisk can be the perfect tool. Consider using flat whisks for stirring hot cereal or porridge of various types. Again its ability to scrape the bottom of the pan is handy, since it means you won’t be burning the bottom of your porridge. This whisk also proves useful for stirring custards or chocolate sauces.