To make the filling, put the speck, bacon, ham and sausage through a meat grinder. Roll the mixture into 10 balls.
To make the potato dough, cook the potatoes in a large saucepan of boiling salted water until tender but still intact. Drain, then peel the hot potatoes and puree with a potato ricer. Cool slightly.
Add the flour, semolina, eggs and salt to the potatoes and knead until a dough forms. Divide the dough in half and form each portion into a thick roll. Cut each portion into 5 thick slices.
Flatten 1 slice and top with a meatball. Enclose in the dough, ensuring the dumpling is well sealed, then roll into a ball. Repeat with remaining dough and meatballs.
Cook the dumplings in lightly salted boiling water, in batches, for 20 minutes or until they float to the surface. Turn occasionally so they don't stick to the bottom.
Serve with sauerkraut or salad.
