Lemon Sauce
One pound sugar; three ounces butter; half a teacup of water. Juice and sliced rinds of two lemons. Pour this into a saucepan, and while it is coming to a boil, beat the yolks of two eggs and add them. When well boiled, take it from the fire and add the whites of the two eggs, beaten to a froth. To be eaten hot with sponge cake.-Mrs. K.
A boiled lemon sauce thickened with egg, in the pudding-sauce tradition that once accompanied every plain cake. The whole thing hinges on how the eggs go in.
- The hinge: temper the yolksBeating the yolks and pouring them straight into a syrup that is coming to a boil will scramble them unless you first slacken them with a ladleful of the hot liquid, whisking hard, then return the mixture to the pan. Keep whisking over the heat until it thickens.
- TeacupA nineteenth-century teacup is usually reckoned at somewhere between 4 and 6 fl oz, so half a teacup is roughly 2 to 3 fl oz of water. That, with one pound of sugar (about 2 1/4 cups), makes a heavy syrup rather than a thin sauce.
- Sliced rindsThe rind is there to perfume the syrup, not to be eaten. Pare it in wide strips with a peeler so none of the white pith goes in, simmer it with the sugar and water, then lift it out before the eggs are added.
- Add the lemon juice lateThe recipe boils the juice with the sugar from the start, as lemon curd recipes usually do. If you are worried about the yolks catching, the juice can instead go in near the end, once the yolks have thickened it.
- "When well boiled"Best read as thickened enough to coat a spoon, in the region of 175-180F rather than a hard boil; an egg-enriched sauce can curdle if held at a rolling boil.
- The whitesBeaten whites folded into a syrup straight off the fire are largely set by the residual heat, but not evenly so. If you are cooking for anyone vulnerable to salmonella, use pasteurised whites, or leave them out and serve the sauce as a thick lemon curd.
- ButterThree ounces is about six tablespoons. The recipe has it in the pan from the start; it can instead be beaten in at the very end, off the heat, for gloss.
- Yield and servingRoughly 2 to 2 1/2 cups, enough for eight or more slices of sponge. It stiffens as it cools, so serve it hot as directed, or chill it and use it as a curd.
Housekeeping in Old Virginia (1877), compiled by Marion Cabell Tyree from contributions by Virginia housewives, is full of recipes signed with an initial like this one, and the sweet sauces have their own section. Boiled and foaming sauces were common at a period when a plain sponge or pound cake was often served without icing or filling; the sauce, poured hot at table, did some of the work that frosting and fruit fillings do now. This one is essentially a lemon curd loosened with water and lightened with beaten whites, a technique shared with the English "lemon cheese" and with the older wine and hard sauces served over puddings.