Calling prunes "dried plums" is misleading. When most people think "plum," they think of the juicy round fruit sold in stores. But if you dehydrate one of those, it won't resemble most people's idea of a prune. Instead of a plump, dark, chewy orb, it will be a flat puddle with a seed bulging in the middle, vaguely reminiscent of the planet Saturn but more pink. And more than likely, that seed will be difficult to extract from the flesh of the dried plum.
There are plums, and there are prune plums. Only one of these is an exceptional laxative. The other, which is typically grown and marketed for eating fresh, is often referred to as the Asian plum. These are juicier than prune plums, with less fiber and sugar. Most varieties of prune plum, on the other hand, are of European descent. They are generally free-stone, meaning the flesh isn't attached to the pit, which makes them easier to process and cook with. The Asian plums are usually of the cling-stone persuasion, meaning the pit is difficult to remove, which doesn't matter as much when you're eating them fresh. You just stop eating when you're down to a tattered layer of fruit fiber stuck to the pit.
There are more differences between Asian-style plums and European-style prune plums. But rarely are these differences felt as dramatically as in a very special torte recipe, popularized by food columnist Marian Burros, that calls for purple Italian prune plums.
"[The prune plums] are engulfed by the batter during baking, and that gives the torte its special quality," explained food writer Greg Patent, who first turned me on to this recipe.
Patent had agreed to walk me through it if I brought the ingredients to his house. The fruit on my Italian plum tree was not quite ripe, so I went to the store. Of course, it only stocked Asian-style plums. I brought those to Patent's house, assuming it wouldn't matter.
He frowned when I arrived with my Asian plums. It had to be purple prune plums, he said, definitively. But we decided to try anyway with the Asian plums, to see what would happen. For comparison, Patent removed a torte from his freezer that was a year old but with the correct fruit.
The torte's magnificence is amplified by the fact that it can survive a full year in the freezer with negligible loss of quality, allowing you to eat purple Italian prune plum torte uninterrupted until the prune plums ripen again the following year. To store a torte, Patent lets it cool completely, wraps it in plastic, then foil, and freezes.
While Patent's year-old torte thawed, we prepared a wrong-fruit torte from scratch. While this year's torte cooled, we reheated last year's at 300 degrees.
The fresh, wrong-fruit torte was delicious, and I wouldn't have had a problem with it were it not for the presence of last year's torte to compare it with. But side-by-side it was evident that the plums in the wrong-fruit torte, being plums and not prune plums, had too much water, which affected the torte's consistency. And their flavor wasn't sweet or assertive enough to balance the cake batter below. The wrong-fruit torte was good but not contagiously outstanding like last year's torte, despite its year in the freezer.
I brought the leftovers to a friend with a sharp sense of taste. Without saying anything about the ingredients or relative ages of the two tortes, I let him try last year's right-fruit model.
"I like it very much," he said.
Then I let him try the new torte, fresh out of the oven.
"This one is less satisfactory," he said. "Something's wrong with the fruit."
Marian Burros' Purple Prune Plum Torte
1 cup sugar (plus a tablespoon or two for the topping)
8 tablespoons (1 stick) unsalted butter
1 cup unbleached all-purpose flour, sifted
1 teaspoon baking powder
Pinch of salt
24 halves pitted Italian prune plums
1 teaspoon ground cinnamon
Arrange a rack in the lower third of the oven. Preheat the oven to 350 degrees. Allow the butter and eggs to come to room temperature. Cream the sugar and butter, either by hand or with a mixer. Add the flour, baking powder, eggs and salt, and mix well. Scoop into a 9- or 10-inch buttered springform pan. Smear the batter so it fills the pan evenly and arrange the plum halves on top with the cut sides facing against the batter, skin sides up. Mix the cinnamon with the 1 or 2 tablespoons of sugar and sprinkle over the top.
Bake for 40 to 50 minutes, until a toothpick inserted into the center pulls out clean. Remove and cool. Use a butter knife to separate the torte edge from the springform, then unclamp and remove the ring.