Watery tomato sauce

It is a reduction, not a thickening

Water leaving is what concentrates the sugars, the acids and the glutamates in a tomato sauce. A sauce cooked for forty-five minutes is not simply thicker than one cooked for fifteen — it is a different and much deeper thing.

This is why adding cornflour or a roux to a thin tomato sauce does not work. The texture improves and the flavour stays thin, and the result reads as tomato soup that somebody has thickened.

The exception is a very short fresh sauce — a summer sauce of raw or barely cooked tomatoes — which is meant to be loose and bright. That is a different dish, and it should be served with a shape that suits it.

What is causing it

• Not cooked long enough. Thirty to sixty minutes for a proper sauce. Fifteen gives a thin one.
• Too narrow or too deep a pan. Evaporation happens at the surface. A wide shallow pan reduces two or three times faster than a saucepan.
• A lid on. A covered pan cannot reduce at all — the steam condenses and runs back in.
• Watery tomatoes. Out-of-season fresh tomatoes are far wetter and blander than a good tin. In winter, tinned is better.
• Too much added liquid. Wine or stock that never got a chance to cook off.
• Wet vegetables added raw — courgette, mushroom and aubergine all release a great deal of water.
• Chopped tinned tomatoes, which are often lower-grade fruit in more juice than whole plum tomatoes.

Reducing it properly

1. Move it to the widest pan you have. This alone often halves the time.
2. Take the lid off. Completely.
3. Keep it at a steady simmer with the surface visibly moving, not a bare tremble and not a boil.
4. Stir occasionally, more often as it thickens. A reduced tomato sauce catches readily.
5. Watch for the oil separating out at the edges and floating on the surface. That is the signal it has reduced far enough.
6. Expect it to darken from bright red to brick. That is the flavour developing, not burning.
7. Season at the end. Reducing concentrates the salt as well as everything else.

Faster routes that are not cheating

A spoonful of tomato purée

Cooked out in the oil first. Adds concentrated tomato rather than starch.

Roasting the tomatoes first

Drives off water and caramelises the sugars before the sauce starts.

A little apple or carrot, grated

Adds body and sweetness. Traditional in several regions.

Passata rather than chopped tins

Sieved and thicker to start with.

A rind of parmesan in the pan

Adds savouriness and a little body, and is a real trick rather than a garnish.

Cornflour

Works on texture and does nothing for flavour. The last resort.

Common questions