Pour the oil into a wide pot and put it on a moderate stove.
Add the onions, very finely chopped. Leave to saute.
In the meantime, chop the potatoes coarsely.
To the sauteed onions add the paprika, salt and stir.
After 10 seconds or so, add the potatoes. Pour in 4 1/5 cups (1 L) hot water and leave to simmer for 15-20 min.
Dilute the flour in a little cold water and pour it into the simmering dish.
Add the chopped parsley and once the dish thickens, remove it from the stove.