The hallmark of a fine fruit sorbet is that it tastes just like the fruit it was made from...only more so. I was thinking about this recently because I had made a batch of plum sorbet while preparing for a class. I occasionally teach plum sorbet in my classes as a means of teaching the basics of fruit sorbets. It is particularly good for this purpose because the final result is so spectacular. Plums produce a sorbet that has an astonishingly vibrant color. And it tastes so very good—far better actually than any plum I have ever eaten.
One of the reasons I think plum sorbet tastes so much better than fresh plums is that my experience of fresh plums has been a bit disappointing. The flesh is extremely sweet while the skin is excessively sour. Eating one becomes a focused exercise in making sure that you have the right amount of flesh and skin in your mouth at the same time so you can enjoy the fruit as I would imagine it was intended to be enjoyed—as a harmonious blending of the sweet and the tart. But inevitably with each mouthful, you end up chewing on that last mouth-puckering piece of skin...all by itself...without the mitigating presence of the flesh. It's just too much work...for an unsatisfactory return. I suppose it's technically possible to peel a plum...but I'm not sure I would want to since the flesh without the skin would be almost too sweet. The depth of flavor added by the sour skin would be missed.
Cooking a plum seems to remedy all of these problems. Through the cooking process there is a magical blending of the sour skin and sugary sweet flesh. The taste of cooked plums is complex—intensely flavorful and almost spicy—with a wonderful sweet-tart balance. I love fruit desserts made with plums...pies & tarts, crisps, cobblers, crostatas...even ice cream served with a simple topping of sugared and roasted plums. My "problem" with fresh plums may simply be that I have never eaten a properly ripened one. But whether or not this is the case, plum sorbet—which is made with plums that have been poached in a sugar syrup—tastes like that fresh, perfectly ripened plum of my imaginings.
In general, one of the reasons a fruit sorbet tastes so purely of fruit is that there is really nothing in it to get in the way of the flavor of the fruit. Besides sugar, the only other addition is usually a little lemon juice. And the lemon juice is only there to enhance the fruit flavor. Lemon is often used in this way in the pastry kitchen. Just as salt is not typically added to make a dish salty, lemon is not always added to make something lemony. Rather, it is added to make something (primarily fruit) taste even more like itself. Sometimes sorbets will include a liqueur or a fortified wine...but like the lemon these are added to amplify, not alter, the flavor.
Any fruit sorbet can be made by following a very simple formula. I have been using the same formula (from my favorite guru of all things technical—Madeleine Kamman) for as long as I have been making sorbets. It is simple, requires no special equipment (other than an ice cream maker), and has never failed me. If you can make a simple syrup, you can make a sorbet. And anyone can make a simple syrup: just combine equal weights of sugar and water in a sauce pan, bring to a boil and simmer for a minute. Store any extra in the refrigerator and use for mixed drinks, fruit compotes...anyplace a little liquid sweetness is wanted.
To make the sorbet, first measure the chopped (or puréed) fruit.
If making an uncooked fruit sorbet (berry or melon, for example), simply combine the puréed fruit with one third of its volume in simple syrup. If making a cooked fruit sorbet (stone fruits or apples/pears, for example), gently poach the fruit in one third of its volume of simple syrup until just tender and then purée.
For both cooked and uncooked fruits, strain the purée if you like. This will insure that the resulting sorbet is silken smooth and free of any remaining bits of skin and fibers—a nice result, but not strictly necessary. Chill the base deeply and just before churning add lemon juice (about 1 1/2 T. per quart of base—but this will vary depending on the fruit).
Before churning, check the sugar density of the base using the "egg test". Place the sorbet base in a tall, deep container. Wash a raw egg well and dry carefully. Drop the raw egg (in the shell) into the sorbet base. Push the egg down so it is submerged and then wait—jiggle the container a bit if you don't begin to see the egg appear on the surface of the mixture. If the sugar saturation of the base is where it should be, the egg will float so that a dime- to quarter-sized portion of the shell is visible on the surface of the sorbet base.
If an area larger than a quarter is visible, add water. If the egg is not visible at all, or the area that is visible is smaller than a dime, add simple syrup. Sorbets that have too high a density of sugar will not set up properly. Conversely, a sorbet with a sugar density that is too low will be hard and frosty. The goal is a well-set sorbet that is smooth and creamy.
This smooth, creamy texture, coupled with the cool and refreshing character of sorbet, may have something to do with the fact that I like plum sorbet better than fresh plums. Perhaps someday I will taste a plum that will alter my opinion. But on a recent hot and steamy day, as I worked my way to the bottom of the bowl, I found it hard to believe that there was a plum out there that I would find any more satisfying.
2 c. water (1 lb.)
2 1/4 c. sugar (l lb.)
1 1/3 lb. ripe plums
about 1 1/2 T. fresh lemon juice
Make the simple syrup: Place the water and sugar in a saucepan and bring to a boil. Boil for one minute. Set aside to cool. You will have about 2 2/3 cup simple syrup, which will keep indefinitely, covered tightly, in the refrigerator.
Halve and pit the plums and cut into 1/2-inch thick slices.
Place the slices in a wide pan and add 1 1/3 cup of simple syrup. Bring to a simmer and simmer gently until the plums are tender—5 to 10 minutes. Using a slotted spoon, transfer the cooked plums to the blender. Purée the plums, adding only enough of the poaching syrup to allow the plum purée to move freely in the blender. Transfer the plum purée to a narrow and deep container and stir in the remaining poaching syrup; chill.
When the base mixture is cold, add lemon juice to taste and test the sugar density using a raw egg (see post text). Freeze according to the manufacturer’s instructions on your ice cream freezer. Transfer to an airtight container and place in the freezer. Makes about 3 cups sorbet.