Put the potatoes into a pot and add water to reach halfway up their sides. Cover the pot, bring to a simmer, and simmer gently for about 30 minutes, or until the potatoes are falling apart. Check the potatoes every 10 minutes to make sure the water is not running dry, and if it threatens to, add a little more.
Drain the potatoes in a colander. Work the potatoes through a drum sieve, ric