Sauce gribiche (boiled-egg mayonnaise)

Separate the boiled egg yolks and press them through a sieve to a fine powder (mashing with a fork works but leaves clumps).

Chop the egg whites into small pieces and refrigerate.

Combine the sieved yolks with a few pinches of salt and pepper, about a tablespoon of Dijon mustard and a tablespoon of vinegar to make the base.

Add the oil very gradually, mixing until each addition is absorbed and the sauce thickens, until all the oil is in; refrigerate to rest.

Finely chop the parsley and the tarragon leaves (plucked from the stems), about a tablespoon of herbs.

Slice the gherkins thinly and roughly chop the capers.

Fold the herbs, capers and gherkins into the mayonnaise, then the chopped egg whites; serve with cold meats or fish.