Mayonnaise

Take the yolks and both oils out an hour ahead, so everything is at room temperature.

Cold is the commonest reason a first mayonnaise splits. A fridge-cold yolk cannot take the oil fast enough and the emulsion never forms at all.

Twist a damp tea towel into a ring and sit the bowl in it, so the bowl stays put and both hands are free.

Whisk the egg yolks, mustard, the 3g of fine salt and the white wine vinegar together for about 30 seconds, until smooth and a shade paler.

Add the neutral oil a drop at a time to begin with, whisking constantly.

Give the first 50ml two or three full minutes and count the drops if you have to. This is the entire recipe. Each drop has to be broken small enough for the yolk to coat it before the next one arrives, and oil poured faster than that simply floats.

Watch for the change about a third of the way through: the mixture stiffens, turns opaque and starts holding the marks of the whisk.

Move to a thin steady trickle once it does, whisking all the while.

Beat in the olive oil last, in the same trickle.

Do not make it with olive oil alone, and do not make it with olive oil in a blender. Shearing olive oil releases bitter compounds, and a mayonnaise that has turned acrid that way cannot be sweetened back.

Loosen it with a spoonful of the warm water whenever it gets so thick that the whisk stands up in it.

Whisk in the lemon juice.

Taste it and add salt if it needs it, bearing in mind it will sit on something else rather than being eaten off a spoon.

If it splits — and you will know, because it goes from thick and pale to a loose greasy curdle in about two seconds — stop whisking at once.

Put the remaining tablespoon of warm water in a clean bowl.

Dribble the split mixture into it a few drops at a time, whisking hard, exactly as you added the oil in the first place.

It comes back. A split emulsion is broken rather than spoiled, and nothing has been wasted.

Scrape it into a clean jar.

Keep it in the fridge and use it within three days. Everything in it is raw and none of it is preserved, which is why it does not keep like a bought jar — that is made with pasteurised egg and enough acid to hold bacteria back.

Put it back in the fridge as soon as it has been served rather than leaving it standing on a warm table.

Treat it as a base rather than a finished thing. It takes garlic, herbs or lemon zest, and it is what turns cold chicken into lunch — the wet brine for chicken and pork in this collection is how to get chicken worth eating cold.

The everyday vinaigrette in this collection is the other emulsion here, held together by mustard rather than by egg yolk. That one is meant to split and be shaken back together; this one is not.