This is the first example of the series; it is that whose preparation is longest and most tiresome; for its principal constituent, whatever this is, must be completely cooked. Its cooking must moreover be coincident with the reduction of the sauce, which is the base of the gratin, and with the formation of the gratin proper, i.e., the crimped crust which forms on the surface and is the result of the combination of the sauce [128] ]with the raspings and the butter, under the direct influence of the heat.
In the preparation of complete gratin, two things must be taken into account:—(1) The nature and size of the object to be treated, and (2) the degree of heat which must be used in order that the cooking of the object, the reduction of the sauce, and the formation of the gratin may be effected simultaneously.
The base of complete gratin is almost invariably ordinary or Lenten duxelle sauce (No. [223]), in accordance with the requirements.
The object to be treated with the gratin is laid on a buttered dish, surrounded with slices of raw mushrooms and chopped shallots, and covered with duxelle sauce. The surface is then sprinkled with raspings, and copiously moistened with melted butter. Should the piece be large, the amount of sauce used will be proportionately greater, and the reverse, of course, applies to medium or smaller sizes.
Take note of the following remarks in the making of complete gratins:—
1. If too much sauce were used in proportion to the size of the object, the latter would cook and the gratin form before the sauce could reach the correct degree of consistence by means of reduction. Hence it would be necessary to reduce the sauce still further on the stove, and thereby give rise to steam which would soften the coating of the gratin.
2. If the sauce used were insufficient, it would be reduced before the cooking of the object had been effected, and, more sauce having to be added, the resulting gratin would be uneven.
3. The larger the piece, and consequently the longer it takes to cook, the more moderate should be the heat used. Conversely, the smaller it is, the fiercer should the fire be.
When withdrawing the gratin from the oven squeeze a few drops of lemon-juice over it, and besprinkle it with chopped parsley.