The encyclopaedia of gravy
Lumps form when dry starch meets hot liquid and gels on the outside before the inside can hydrate. Prevention is easy; the cure is a sieve.
Why lumps happen¶
Starch granules swell and gel when they meet hot water. If a clump of dry flour hits hot liquid, the granules on the outside of the clump gel instantly and form a waterproof skin. The dry flour inside is then sealed off, and no amount of stirring will hydrate it.
That is a lump: a parcel of raw flour in a cooked wrapper.
The three prevention methods¶
1. Disperse in fat (a roux). Coating each flour particle in fat keeps them separate when the liquid arrives. This is why gravy recipes cook flour in fat first.
2. Disperse in cold liquid (a slurry). Cornflour and flour both mix smoothly into cold water. The starch does not gel until it is heated, so by the time it does, it is already evenly spread.
3. Add liquid gradually. Even with a good roux, dumping 500 ml of cold stock into hot roux in one go can shock it into lumps. Add a ladleful, stir it completely smooth, then add the next.
💡 Chef's tip
Hot liquid into hot roux, or cold liquid into cooled roux. The combination to avoid is hot roux, cold liquid, all at once.
Fixing lumps that have already formed¶
In order of escalation:
- Whisk hard. A balloon whisk breaks up most soft lumps in thirty seconds.
- Sieve it. Pour the gravy through a fine sieve into a clean pan, pressing with a spoon. This works every time and costs you nothing but a washing-up item.
- Blend it. A stick blender in the pan destroys lumps completely. Use it briefly — over-blending a flour gravy can make it gluey.
- Start the thickening again. Strain out all the solids, then re-thicken the clean liquid with a cornflour slurry.
Lumps that are not lumps¶
Two things often mistaken for lumps:
- Bits of fond, herb or vegetable. Harmless and often delicious. Strain if you want a smooth gravy.
- Skin. The film that forms on standing gravy is protein and starch drying at the surface. Whisk it back in, or cover the surface with a disc of greaseproof paper while it waits. See keeping gravy warm.
Reputation¶
If you serve someone gravy that has lumps in it, they might say things behind your back.