Peel and slice potatoes, boil in the salted water until done. Peel the onion, chop, sauté in the 1 tablespoon butter , add the stewed beef, fry all together. Drain the water from potatoes, add the butter and milk, mash into a puree. Add the stewed beef with onion, stir, salt and pepper. Serve with fried eegs, pickles and herringe.