Potato prep. Boil potatoes in salted water (I like 1 tsp salt per quart) until soft, then mash smoothly.
Plum prep. Wash and half-pit plums, ensuring they stay connected, and sprinkle 1/4 tsp sugar on each.
13 to 20 plums, sugar
Make dough. Mix mashed potatoes, flour, starch, and egg. Begin with a spoon and transition to hand-kneading until a cohesive, slightly sticky dough forms.
1 pound cooked potatoes, 1 1/2 cups all-purpose flour, 2 tablespoons potato starch or cornstarch, 1 egg
Make dumplings. With floured hands, tear dough, form a ball, and flatten into a circle. Encase a sugared plum, adjusting dough as needed, and roll in hands to even out.
Boil. In boiling salted water (1 tsp salt/quart), cook dumplings until they float, then simmer for an additional 4-5 minutes. Use a slotted spoon for removal and draining.
salt
Serve. Serve hot and enjoy with optional sweet toppings like sugar, honey, or a berry sauce.