Your dried-out bread should correspond, as nearly as possible, to the coarse, vulgar, compact, heavy loaf of sourdough peasant bread.
The onions should be of tender-fleshed sweet variety, softening readily and uniformly in cooking—the large white summer onions or violet Bermudas. Some of the yellow-skins are sweet, other varieties tough and strong (if only the latter are available, don’t renounce).
The cheese must be freshly grated and only two—either singly or together—are ideal; Swiss Gruyère and Italian Parmesan. The Swiss cheese should never be soft and elastic—these are the qualities that transform the eating of onion soup into a taffy-pulling contest. A good Gruyère, less than half the size of the
Parmesans pose less of a problem. Cylinders of
A wide-mouthed earthenware vehicle, broader than it is high (leaving the largest possible surface for the gratin to form) is perfect and may be used, as well, for coloring the onions (protected by an asbestos mat from the direct flame). If enameled ironware is to be used, the onions should be colored in another heavy vessel—copper, earthenware, cast-iron, since an enameled surface does not color them correctly.
The mind rarely registers weights and measures in terms of visual bulk. The precision of the measures given here could not be of less importance; the thing to remember is that there should be lots of onion, lots of bread, and lots of cheese in relation to the (undetermined) amount of water. Just before putting the casserole into the oven, the surface may, if one wishes, be sprinkled with Cognac.
Cook the onions, lightly salted, in the butter over a very low heat, stirring occasionally, for about 1 hour, keeping them covered for the first 40 minutes. If the heat is low enough and the saucepan of a heavy material, there will be no problem of coloration—they should begin to caramelize lightly toward the end of an hour’s time, at which point the flame may be turned up slightly and they should be stirred regularly until the entire mass is of a uniformly rich caramel color. Should there be signs of coloration too soon, the flame should be lowered even more, or the heat may be dispersed by separating the pan from the flame with an asbestos pad.
Spread slices of bread thickly with the onions, arrange a layer in the bottom of the casserole, sprinkle over a thick layer of cheese, and repeat the process, packing each layer gently and arranging the bread slices as well as possible to avoid empty spaces. The onions should be used up on the next to last layer of bread, the last layer being sprinkled only with cheese, and the casserole should not be more than two thirds full at this point.
Pour in the boiling, salted water, slowly and very carefully, at one single point against the side of the casserole, permitting the bread to swell and the mass to rise about 1 inch, or until obviously just floating, but no more (if you fear an unsteady hand, carefully ease the tip of a funnel down the side of the casserole to the bottom and pour the boiling water into the funnel).
Cook on top of the stove, uncovered, over a very low heat, the surface maintaining a light, slow bubble for ½ hour. Add, as before, just enough boiling water to be certain that the body of the bread is submerged, sprinkle a bit more cheese over the surface (sprinkle over Cognac now, if you like), shave paper-thin sheets from a firm, cold block of butter, distributing them over the surface, and transfer the casserole to a medium oven (325° to 350°) for 1 hour, raising or lowering the temperature, if necessary, after about 40 minutes’ time, depending on how the gratin is developing. The soup should be covered with a richly colored crust of gratin and should be served out with a large spoon onto preheated plates.
Copyright © 1974 by Richard Olney. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.