When making dumplings, always cook a sample first. If the dumpling is too soft, add dry rolls soaked in water; if it falls apart then mix some flour of breadcrumbs into the dough.
2lbs raw potatoes
3/4 lb boiled potatoes
1/2 c milk, boiling
1 bread roll
1 1/2 tbs butter
Grate the raw potatoes into some vinegar-waver. Wrap in a linen cloth and press out as much liquid as possible.
Immediately pour over the boiling milk. Grate the cooked potatoes and combine these with the raw ones. Add salt and stir in egg. Make a sample dumpling. If it turns out, form more dumplings with wet hands. If not, see above note.
Into the middle of each ball, press some croutons, then drop the dumplings into boiling salted water and simmer until done for 20-30 minutes with the lid half open. Serve with beef and saurkraut.
This is translated straight from German, so the grammer isn't the best.