Step 3: Thicken
This is the step that changes the dripping into thick gravy. One of the best ways to thicken sauces is with a roux, a method that pairs equal parts fat and flour.
Combing flour and fat together BEFORE adding to the liquid prevents clumping and creates thick, velvety smooth gravy. Eight tablespoons of roux will thicken 1 litre of gravy.
Here is how you make a roux. Add 4 tablespoons of the reserved fat to a saucepan over medium heat. This is where a saucepan with slanted sides comes in handy. When the fat is melted, add 4 tablespoons of flour and cook, whisking constantly, for 3-4 minutes until the roux turns a light golden colour.
When the roux is cooked and smooth, add the simmering stock, whisking gently. Simmer over medium heat, stirring occasionally, for 5-10 minutes or until thickened.
The flavour intensifies as the liquid cooks down. So taste your gravy before seasoning, adding salt, pepper and minced fresh herbs to taste.