Our favorite ex-neighbor Jess told me the low sugar plum preserves I’ve been making are an ancient German thing called Pflaumenmus. Pflaume translates to plum, Mus to mash, but here it’s for a thick, cooked down sauce. Since peaches and plums are both stone fruit, I used the same technique for this Pfirsichmus (pfeer-seesh-moose).
For the shopping list
Peaches (or Plums)
10% of sugar by weight (If you don’t have a scale, use about 1 1/2 tablespoons of sugar for each cup of fruit.)
From the kitchen
4 quart Pan
For the plums I get the best results with smaller batches, no more than 5 pounds of fruit. It makes it easier to cook without burning.
I don’t peel the plums, but peach skins get tough when cooked. A serrated edge swivel peeler will do the job, but the quickest and easiest method is dropping the fruit into boiling water for about a minute. Do a few at a time, lifting them out of the water with a slotted spoon; transfer to a bowl to cool, then slip the skins off.
Hold the peeled peaches over a bowl to catch the juices while you cut them. Freestone peaches can be sliced in half and the pit lifted out. For cling peaches, hold the fruit in one hand while you cut thin slices, lifting each one off the stone as you cut it. I cut the fruit into smaller chunks as I’m pitting, then put those in a food processor to make a chunky puree.
Weigh the prepared fruit and mix in about 10% sugar by weight. It’s much easier to calculate if you set your scale to grams, but you can also enter “10% of 5 lbs” in Google and get the answer. If you don’t have a scale, use about 1 1/2 tablespoons of sugar for each cup of fruit.
Mix the fruit and sugar, cover, and let sit overnight or for a few hours. Transfer to a wide, shallow pan (for a full 5 lbs of fruit you may need two pans) and bring to boil, stirring often to prevent scorching. Keep it at a full, robust boil for about 10 minutes, stirring constantly.
Remove from the heat and let cool completely in the pan. If you want a thicker Mus, boil it for another 10 minutes after it’s cooled for several hours. The Pfirsichmus will keep in the refrigerator for a week or more, or it can be frozen.