Creamy and a little bit sweet, this sauce is the perfect match for grilled pork chops or chicken cutlets.
Preheat the oven to 425°. On a large rimmed baking sheet, toss the parsnips, shallot, and garlic with the oil; season with salt and pepper. Spread the vegetables out in a single layer. Roast until the parsnips are tender and light brown in spots, 20 to 25 minutes. Scrape the vegetables and any juices into a blender. Add the sour cream, lemon juice, and 1/2 cup hot water. Puree on high until smooth, about 1 minute. Add more hot water as needed to loosen the sauce; season.