Smashed Fingerlings with Jalapeños

This recipe comes from Bon Appetit contributed by Lou Lambert and Larry McGuire. I liked it but it was not special. It was too vinegary. I like fingerlings with jalapeños just straight without the sauce. You can always throw in some whole garlic cloves.

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

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.