How do I reduce a sauce?

Reduction is evaporation. Everything that matters follows from that: surface area speeds it up, a lid stops it entirely, and everything already dissolved in the liquid — including salt — gets more concentrated as the water leaves.

What you'll need

• Wide pan
• The sauce
• Wooden spoon (optional)

Step by step

1. Move it to the widest pan you have.Evaporation happens at the surface. A wide sauté pan reduces several times faster than a tall saucepan holding the same liquid.
2. Leave it uncovered.A lid returns the condensing steam to the pan. With a lid on, a sauce will not reduce at all.
3. Keep it at a brisk simmer, not a rolling boil.Hard boiling can split dairy-based sauces and scorches the base of thick ones. A steady simmer is faster than it looks.
4. Stir occasionally, more as it thickens.Thicker sauces catch and burn on the base. The last few minutes need attention.
5. Judge by coating, not by volume.Draw a spoon through it — the sauce should coat the back and hold a line when you run a finger across.
6. Season only at the end.Salt does not evaporate. A sauce seasoned before reduction can end up inedible by the time it is thick.
7. Finish off the heat with butter if you want gloss.A cold knob whisked in off the heat gives shine and body. On the heat it separates.

Tips

• Reducing sweet things concentrates the sweetness too. Taste as you go with anything containing wine, fruit or tomato.
• If you need it thicker but cannot reduce further without over-concentrating, thicken with a little cornflour slurry or a roux instead.
• Cream reduces well and rarely splits. Milk and yoghurt do not — add those at the very end, off the heat.

Common mistakes

• Seasoning before reducing — Salt stays behind as the water leaves, so the finished sauce can be far too salty.
• Reducing with a lid on — The steam condenses and drops back in. Nothing evaporates and nothing reduces.

Questions people ask