Serves 8
2 pounds small red potatoes, halved or quartered if large
2 T olive oil
2 T whole-grain Dijon mustard
1/2 tsp. kosher salt
1/4 tsp. freshly ground black pepper

Arrange a rack in the middle of the oven and heat to 425°F. Place all the ingredients in a large bowl and toss to combine. Transfer the potatoes to a rimmed baking sheet and arrange the potatoes so they are cut-side down.
Roast for 10 minutes. Flip the potatoes over with a flat spatula and cook until browned and tender, about 10 minutes more