Mashed Japanese Sweet Potatoes

Ingredients

Rinse and peel the skins from the sweet potatoes and cut into cubes (about 1 inch in diameter.)
Place the cubes in a large pot and cover in water so that the water comes just to the top of the cubes. Add a pinch of sea salt to the water.
Bring to boil and let the cubes cook in the boiling water for about 15 minutes. The cubes are ready when they are easily able to pierce.
Drain the water and place the cubes in a bowl. Using a mixer, whip the sweet potatoes for 1-2 minutes.
Add the butter and let melt for a few minutes then add milk and whip up until fluffy.
Add walnuts if desired.
Add salt and pepper to taste.

Source: Tested by Cindy Bevans