To add some zazz to the standard roasted potato side dish, we spiked this recipe with two different kinds of mustard. First, coat tiny marble potatoes with whole-grain mustard and olive oil, then roast them with sliced onions until tender and browned. Just before serving, stir in some sharp Dijon to coat the hot potatoes. r.
1/4 cup olive oil
1/4 cup whole-grain mustard
2 pounds marble potatoes (about 1 inch in diameter)
Freshly ground black pepper
1 medium yellow onion, halved and thinly sliced
1 tablespoon Dijon mustard
Heat the oven to 475°F and arrange a rack in the bottom third.
Whisk the oil and whole-grain mustard in a large bowl to combine. Add the potatoes, season with salt and pepper, and toss to combine. Transfer the potatoes to a rimmed baking sheet and spread in an even layer. Reserve the bowl (no need to wipe it out).
Roast the potatoes for 15 minutes. Remove the baking sheet from the oven, add the onions, and stir to combine. Return the baking sheet to the oven and continue to roast until the potatoes are knife-tender and the onions are browned, about 15 minutes more.
Transfer the vegetables to the reserved bowl, add the Dijon mustard, and toss to combine. Taste and season with additional salt and pepper as needed.