Cherry Jelly

A clear fruit jelly of the old school: sugar syrup clarified until bright, cherries steeped in it off the heat, and the whole set with isinglass and sharpened with lemon. The original gives no quantities, so treat it as a method rather than a formula.

• The hinge: never add the setting agent to hot syrupThe hinge: add the setting agent to cold liquid -- The instruction to take the pan off the fire and wait until the decoction is cold before adding the isinglass is worth following, since prolonged heat weakens gelatine's setting power. Note that the cherries themselves do go into the syrup while it is still boiling; it is the isinglass, specified as 'cold', that is kept off the heat.
• Clarified sugarThis means a syrup boiled with egg white (or in later practice simply skimmed carefully), the scum lifted off so the liquid runs bright. Modern refined sugar needs no clarifying for cleanliness, but skimming the foam still matters if you want a jelly you can see through. A syrup of roughly 2 parts sugar to 1 part water by weight is in the right range for a fruit jelly.
• IsinglassIsinglass is a gelatine made from the swim bladders of sturgeon and similar fish; it is now sold mainly to brewers and winemakers for fining. Use plain powdered or leaf gelatine instead. One envelope of powdered gelatine (about 2 1/4 teaspoons) per 2 cups of strained liquid gives a soft set; for a jelly firm enough to turn out of a mould you will want appreciably more. Since the original specifies neither the volume of syrup nor the weight of isinglass, expect to test a spoonful on a cold saucer.
• Quantities are absentNo weight of cherries, sugar or isinglass is given. A workable starting point is 2 lb stoned cherries steeped in about 3 cups of clarified syrup.
• The lemonsThree or four lemons is a great deal of acid for a small quantity of jelly. Add the juice of two, taste, and go on from there; the acid is there to cut the sugar and brighten the colour, not to dominate.
• Straining through a bagA jelly bag of flannel or several layers of muslin, hung and left to drip. Do not squeeze or press it, or the fine cherry solids will pass through and cloud the jelly. Straining a second time through the same bag gives a noticeably clearer result.
• The earthen mouldThe original calls for an earthenware mould; a metal or plastic jelly mould works as well. Rinse it with cold water rather than oiling it, and chill at least 4 to 6 hours before turning out.
• Cherries and stonesSour cherries (morello, montmorency) give far more flavour and colour to a steeped jelly than sweet dessert varieties. Stone them before steeping; whole stones left in a cold infusion contribute little beyond the risk of a cracked tooth.
• YieldThe suggested proportions above should fill a mould of roughly 1 quart, enough for six to eight as a dessert.