(I had larger plums, but if you use smaller Bistrita plums, several pieces will come out.) The plums are washed, wiped with a paper towel, cut in half and the seeds removed. Melt the butter in a non-stick pan, add the breadcrumbs and brown until golden.
Boil water, oil and salt. When the water starts to boil, set aside and add all the flour. Mix quickly with a wooden spoon and set aside to cool a little, as much as you can knead by hand. Add the egg and knead by hand until the egg is incorporated into the dough. The dough will be elastic and non-sticky. If it sticks to your hand, add a little more flour.
From the dough, make a thicker roll on the floured board and cut pieces of about 2 cm. Flatten by hand, put half a plum and wrap. Give each dumpling through the flour so that it does not stick to the work table until you have finished making them all. Boil in boiling water with a little salt. Remove with a spatula and roll in browned breadcrumbs. Serve with sugar and cinnamon.