Here is my recipe for the best mashed sweet potatoes ever.

4 large sweet potatoes (do not use yams!)
4 tbsp (one-half stick) Earth Balance Buttery Sticks
1/2 to 3/4 cup soymilk
salt and pepper to taste

Boil the potatoes in a large stockpot until fork tender.
While hot, add 1/2 cup of the soymilk and all of the buttery stick.
Beat with a hand blender, adding more milk until smooth and fluffy.
Add salt and pepper to taste.

Yum!