The encyclopaedia of gravy
Flour and cornflour both thicken gravy but behave completely differently — in appearance, mouthfeel, stability and how they are added.
Both work. They are not interchangeable.
Side by side¶
| Plain flour | Cornflour | |
|---|---|---|
| Appearance | Opaque, matte, traditional | Glossy, slightly translucent |
| Thickening power | Moderate | About twice as strong by weight |
| Dose per 500 ml | 30 g (2 tbsp) | 15 g (2 tbsp, lighter) |
| How it's added | Cooked in fat as a roux | Mixed with cold water as a slurry |
| Cooking time after | 5–10 minutes | 1–2 minutes |
| Raw taste | Yes — must be cooked out | Minimal |
| Freezes | Well | Badly — goes watery |
| Long simmering | Stable | Thins if boiled hard |
| Gluten-free | No | Yes |
| Best for | Roast-dinner gravy, white gravy | Chinese-style sauces, last-minute fixes, gluten-free gravy |
Flour: the roux method¶
Cook equal weights of fat and flour for 2–8 minutes, then add liquid gradually. See making a roux.
Flour gives the matte, slightly cloudy look most people picture when they think of gravy, and a fuller mouthfeel. It also carries flavour, because the roux itself browns and tastes toasted.
Cornflour: the slurry method¶
- Mix cornflour with cold water, about 1 part cornflour to 1.5 parts water, until perfectly smooth.
- Pour into simmering liquid while whisking.
- It thickens within 30–60 seconds.
- Simmer no more than 2 minutes.
Cornflour gives a clear, glossy sauce and a lighter, more slippery texture. It is the fastest fix for a gravy that is too thin.
⚠️ Watch out
Never add dry cornflour to hot liquid. Each grain gels on the outside instantly and seals dry powder inside, producing lumps that will not disperse. Cold slurry always.
A third way: beurre manié¶
Equal parts soft butter and flour mashed to a paste, whisked into hot gravy a small piece at a time. It thickens like a roux without needing to be made first, and is the classic rescue for a gravy that is too thin at the last minute. Simmer for 3–4 minutes afterwards to cook the flour.
Other thickeners¶
| Thickener | Notes |
|---|---|
| Arrowroot | Glossiest of all, clear, gluten-free; thickens at lower temperature, fussy about reheating |
| Potato starch | Very glossy, gluten-free, breaks down with long cooking |
| Mashed potato or a blended vegetable | Rustic, adds flavour, matte finish |
| Reduction alone | No starch at all — see jus and reducing stock |
| Gravy granules | Contain starch plus flavouring; see instant gravy granules |