Roasted Roots with Gremolata Butter

1 lb. mixed root vegetables (yams, parsnips, salsify, carrots, Jerusalem artichokes, rutabaga, turnips), peeled
1 lb. fingerling potatoes, scrubbed
3 tsp. extra-virgin olive oil
1 tsp. fresh rosemary, chopped
Kosher salt and freshly ground black pepper
2 tsp. Italian parsley leaves
1 large clove garlic
Zest of 1 lemon
2 tsp. butter, room temperature

Place a heavy rimmed baking sheet in the oven and preheat to 400 degrees. Cut the root vegetables and potatoes into equal-size sticks, quarter-inch thick and three inches long. In a large bowl, toss them with the oil, rosemary and salt and pepper. Pull out the oven rack that holds the preheated baking sheet and tip the mixture into the pan, which sears the mixture and reduces the likelihood of sticking. Roast the vegetables, stirring once halfway through cooking, until the pieces are tender, about 25 to 30 minutes. Meanwhile, place the parsley, garlic and lemon zest on a cutting board with a generous pinch of salt and finely mince them. Place this mixture in a large bowl and stir in the butter. Toss the vegetables with the butter mixture and serve hot.