Roux vs. Slurry: What’s Best for Gravy?

A good gravy is a mighty fine thing — whether draped over mashed potatoes, turkey and stuffing, or french fries, or perhaps served in a little cup for dunking a good sandwich into. A good gravy should be meaty, rich, savory, and (ideally) smooth as silk. Traditionally thickened with flour, gravy can take one of two paths for guaranteed smooth results that are free of lumps: Starting with a roux or ending with a slurry. Which strategy is best for gravy? To determine the answer, I got in the kitchen and did some testing.

First up was roux, a mixture of one part flour and one part fat that’s cooked until it’s smooth and reaches your desired color (more on this in a sec). After the roux is made, liquid is incorporated until you end up with a thickened sauce. For my roux testing, I used butter for the fat (you could use any fat — oil or meat drippings would also work well) and worked with store-bought chicken stock for the liquid.

The stages of roux are determined by the color it reaches: white (notably used for white sauce), blonde (often used for gravy), and brown or dark (the starting point of gumbo). For me, the stage somewhere between blonde and dark — when it’s the color of peanut butter — worked best, imparting nutty notes and offering good thickening properties.

The “equal parts fat and flour” part of roux is interpreted two ways, and I tested both. First up was measuring equal parts by weight, which translated to 2 tablespoons flour and 1/4 cup flour. I melted the butter in a skillet over medium-low heat, stirred in the flour, and cooked it until it was the color of peanut butter. The roux was very thick, similar in texture to miso or a hefty hummus, so I mashed it around the pan with a silicone spatula. Whisking constantly, I then gradually added 1 cup chicken stock, then increased the heat to medium and cooked for a couple of minutes until thickened, whisking frequently. For me, this ratio made for a roux that was a little difficult to work with, and the gravy was too thick — so on to the next test I went.

I then tested by using equal parts flour and fat by volume (2 tablespoons butter and 2 tablespoons flour). I followed the same process: Melted the butter over medium-low, added the flour and whisked until peanut butter–colored, and then gradually whisked in 1 cup chicken stock. I then raised the heat to medium and cooked until thickened, whisking frequently. This ratio worked better for me; the roux had the viscosity of cooking oil and was easy to whisk as it cooked. The gravy was the ideal texture: thick enough to coat a spoon, and not gloppy or watery. 

I also tested thickening gravy with a slurry, a mixture of flour whisked into cool or room-temperature liquid until smooth, then added to simmering stock. I whisked together 1/4 cup room-temperature stock and 2 tablespoons flour and set that aside as I brought 1 cup of stock to a boil in a saucepan. Whisking the liquid constantly, I gradually added the slurry and cooked for a minute or two until I achieved a thickened gravy with a very similar texture to my second roux-based gravy.

So, which method was best? Of course, that’s based on personal preference, so let me start by assuring you that both work very well to create a smooth gravy that’s perfect for drizzling. The slurry-based gravy was silky and very smooth. The roux-based gravy was slightly less silky than the slurry one, but it made up for that in flavor — and that’s the one that I preferred. Flour browned in fat simply lends so much more savory richness to gravy; the taste always reminds me of fried chicken crust. Roux-based gravy just has more depth.

To recap, both methods work, and here are the ratios I used to thicken 1 cup of liquid.

• Roux: 2 tablespoons fat (I used butter) and 2 tablespoons flour
• Slurry: 1/4 cup liquid and 2 tablespoons flour

One final note: I also tested the roux and slurry methods using a gluten-free all-purpose flour blend (specifically, King Arthur’s Measure for Measure flour). I did not test a gluten-free version using cornstarch, by the way, because I don’t like the semi-translucent, gelatinous look and texture of cornstarch-thickened gravy. Here are my findings from testing with the gluten-free flour blend.

• Roux: Using the same ratios stated above, the flour browned well and thickened the gravy nicely. There was a slight chalkiness to the gravy, but once it’s draped over your food, you might not notice that.
• Slurry: Using the same ratios above, the gravy ended up very thick, with a slightly gelatinous appearance. I would not recommend this.