Place 40 g (1½ oz) freshly skinned pistachio nuts and 25 g (1 oz) pine seed kernels or if unavailable, 25 g (1 oz) skinned sweet almonds, in a mortar and pound to a fine smooth paste adding a little less than 1 tbs of cold Sauce Béchamel; pass it through a fine sieve. Place the purée in a basin with 6 egg yolks, a pinch of salt and a little pepper and mix together with a whisk proceeding as for Mayonnaise by adding 1 litre (1¾ pt or 4½ U.S. cups) oil and the juice of 2 lemons.
Prepare ¾ dl (3 fl oz or ⅜ U.S. cup) of a purée composed of equal quantities of parsley, chervil, tarragon, chives and fresh pimpernel, rapidly blanched for 2 minutes then drained, refreshed, squeezed thoroughly and passed through a fine sieve. Mix into the sauce.
This sauce is usually served as an accompaniment with cold fish.