The mustard coating on the potatoes gets crunchy and dark while the insides stay creamy and sweet. This serves 10.
Position two racks in top and bottom third of oven. Preheat to 425°F.
Spray 2 large rimmed baking sheets with nonstick spray.
Whisk mustard, olive oil, butter, lemon juice, garlic, oregano, lemon peel, and salt in large bowl to blend. Add potatoes; sprinkle generously with freshly ground black pepper and toss to coat.
Divide potatoes between prepared baking sheets, leaving any excess mustard mixture behind in bowl.
Spread potatoes in single layer. Roast potatoes 20 minutes. Reverse baking sheets and roast until potatoes are crusty outside and tender inside, turning occasionally, about 25 minutes longer.
You can make the dish up to two hours ahead and let them stand on the baking sheets at room temperature. Rewarm potatoes in 425°F oven 10 minutes.
For a December dinner I was worried about a traffic jam of dishes that needed to be in the oven to cook. This was in Fine Cooking and when I saw that it could be made a head, and better yet, the potatoes did not have to be peeled, it was a go.
The potatoes were great!