Peel and quarter potatoes. Place in a medium sauce pan, add water to barely cover potatoes. Add 1 teaspoon salt. Bring to a boil. Lower temperature to a simmer. Let cook until potatoes are tender, about 20 minutes. Remove from heat.

Drain potato water into a container. Set aside.
Add vegan margarine to the potatoes. Stir to coat potatoes with margarine. Use a potato masher to mash the potatoes.

Measure 1 1/2 cups potato water into a blender. Add 1/4 cup cashews. Blend on high until smooth (2 min.) Add to potatoes a little at a time while stirring, making sure you do not add too much liquid. When the mashed potatoes reach the right consistency salt to taste.