In a big pot submerge potatoes in water. Put the lid on and bring it to boil. Mind to wash the potatoes beforehand or if bought washed just rinse them under running water.
Reduce heat to medium low and cook the potatoes until soft in the inside. Test by sticking a knife into one of the bigger ones. If the knife goes through softly without much effort the potatoes should be ready.
Drain the water, add sour cream and salt.
Mash the potatoes until a uniform texture achieved. A kitchen robot with a whisk attachment will come quite handy.