reduce heat simmer covered til potato is just tender.
add sour cream stir til heated through.
remove from heat stir in parsley.
IF you want your soup a bit thicker I quickly use a hand held blender and pulse it a couple of times but dont completely blend it or it will be too thick still leave some potato chunks. tastes even better the next day.
you can also use 1kg of bintje or pink fir apple potatoes.