Get ready. Preheat the oven to 400ºF. Divide the thick top of the parsnips from the slender ends. Cut the thickest part lengthwise into halves or quarters (they should be about 1 inch wide at the thickest part). All the pieces should closely match in size.
Simmer the parsnips. Put the parsnips in a large skillet or metal roasting pan large enough to contain the parsnips in an even layer. Add the oil and salt and toss to combine. Arrange parsnips in a single layer and add the water. Bring to a simmer over high heat.
Roast the parsnips. Transfer the skillet or roasting pan to the oven and roast, stirring once, until the parsnips are fork-tender, 20 to 30 minutes. The water will have nearly evaporated.
Make the mustard glaze. Mix the honey, mustard, and vinegar in a small bowl. Add to the parsnips, stir gently making sure not to break up the parsnips, and roast until deep brown and glazed, 10 to 15 minutes.
Finish and serve. Transfer the parsnips to a serving bowl and garnish with the parsley and nuts. Serve immediately.
Notes
Shop this recipe: Visit our shopto browse quality Mediterranean ingredients, including the olive oil and honey used in this recipe.
To roast hazelnuts: Place raw hazelnuts on a small rimmed baking sheet and bake in a 325ºF oven until the dark skins have cracked and the nuts smell buttery, 15 to 20 minutes. Rub the warm nuts in a dish towel to remove the papery skins.
How to select parsnips: Choose squat, wide parsnips that are fairly uniform in width throughout for the most even cooking. Pass on parsnips with very long spindly tips.