Half an ounce of butter.
Three teaspoonfuls of vinegar. Salt and cayenne.
Remove the heads and tails of the fish; split them open, and remove the backbones; then lay the two halves together. Heat the sardines on a tin in the oven; lay them, when hot, on the toast, and keep them hot. Melt the butter in a small saucepan. Whisk the yolks and white well together. Add the vinegar and seasoning. Whisk the mixture over a slow fire until it becomes as thick as good cream. It must not boil. Pour it at once over the sardines. Sprinkle the surface of each with chopped parsley and red Hungarian pepper, and serve immediately.