1 lb. red potatoes (about 8 large ones)
salt and pepper
1/2 cup milk, half and half, or cream*
3 T. butter
1/2 cup sour cream
Wash potatoes (don't peel) and slice into 2-inch chunks. Put in a pan and cover with water. Bring to a boil, and salt water generously (potatoes need salt!). Boil for 10-15 minutes, until tender. Drain and place in bowl. "Smash" potatoes, skins and all with a potato masher or large fork. It's okay if there are a few chunks.
Heat milk for 60 seconds in the microwave or until warm; stir into potatoes. Stir in butter until melted. Right before serving, stir in sour cream, salt, pepper. You can add green onions and/or cheese if you like.
*Note: I usually have skim milk and cream on hand. That way I'm prepared for any kind of dairy called for in a recipe because I can mix them together. Also, high-fat dairy stays good longer than low-fat, so I can buy a cheap quart of cream at Costco and it can last for two months. You can also freeze cream.