Buttermilk Mashed Potatoes

1 1/2 lbs (4 medium) potatoes, peeled and cut into 1 inch pieces
Coarse salt and fresh pepper
1/4 to 1/2 cup buttermilk
2 tbsp butter

Peel and chop potatoes, and place them in a large saucepan. Add enough cold water to cover by 2 inches. Turn heat to high, and bring to a boil. Add 1 tbsp of salt and cook until very tender about 20-25 minutes. Drain and place back in the same pot. Mash with a potato masher, then add buttermilk and butter. Season with salt and pepper. Mash until smooth and combined.