Sour Cream Mashed Potatoes

3 lbs. potatoes, peeled and quartered

1/4 lb. butter

1/2-1 c. milk

1/2 c. sour cream

2 tsp. salt

1/2 tsp. ground pepper*

Cook the potatoes in a large pot of boiling salted water for 15-20 minutes until very tender.  Meanwhile heat the butter and milk in small sauce pan (or in microwave).  Drain potatoes.  While still hot, place the potatoes in a big bowl.  Slowly add the milk and butter mixture, sour cream, salt, and pepper.  Mix until the potatoes are mashed but not completely smooth.