Ingredients
3 pounds fingerling potatoes, halved crosswise if large
½ cup olive oil, divided
Kosher salt and freshly ground black pepper
¼ cup Sherry vinegar or red wine vinegar
1 tablespoon whole grain mustard
1 jalapeño, thinly sliced into rounds, seeds removed if desired
¼ cup (lightly packed) torn flat-leaf parsley leaves
Preparation
Preheat oven to 450°. Toss potatoes with ¼ cup oil on a rimmed baking sheet; season with salt and pepper. Roast, tossing once, until golden brown and tender, 30-35 minutes. Let cool slightly, then lightly flatten.
Meanwhile, whisk vinegar and mustard in a large bowl. Gradually whisk in remaining ¼ cup oil until emulsified; season with salt and pepper. Add potatoes, jalapeño, and parsley and toss; season with salt and pepper.
