Grainy Mustard Smashed Potatoes

(from Cooking Thin with Chef Kathleen)

Makes 4 to 5 servings

1 ¼ pounds small potatoes
1 tablespoon butter
2 tablespoons grainy mustard
Coarse-grained salt and cracked black pepper

Place potatoes in a large pot and cover with cold water. Bring to a boil, reduce heat to a simmer, and cook until fork-tender, 12-16 minutes. Drain potatoes and place back in pot you them in. Add butter and mustard. Using a potato masher, smash until coarse and very chunky. Season with salt and pepper; taste and adjust seasonings. Serve immediately.