Compared to vibrant spring and summer produce, winter vegetables are often overlooked and unloved by the food community. The season's bounty of produce like leeks, fennel, root vegetables, carrots, and dark greens may not stir up the same sort of gushing emotion as colorful heirloom tomatoes, asparagus, and elusive fava beans, but when prepared well, winter produce can be surprisingly enticing. Winter wouldn't be winter without soul-satisfying gratins, delicious and hearty soups, and comforting braised winter greens with nurturing root vegetables.
Braised, roasted, stewed or pureed, root vegetables can truly stand out in the winter months without being too fussy or complex. Root vegetables like turnips, rutabaga, and celery root contain nutrients like fiber, magnesium, potassium, thiamin, vitamin B6, and vitamin C. In addition, turnips are high in calcium and rutabagas are packed with vitamin A. Yukon gold potatoes are high in fiber, potassium, and vitamin C.
I had not worked with celery root before making this dish and found it rather daunting. Celery root may sound unappealing if you don't like celery, but don't be so quick to judge, celery root can be full of wonderful spicy and refreshing flavor. Celery root is about the size of a grapefruit with a few tough, dark green stalks growing on top and roots growing on the bottom. Choose the celery root that is the heaviest for its size as it is more likely to be dense and tender. Slice off the top and bottom of the root and peel the outside with a good vegetable peeler. If not using immediately, submerge the celery root into cold water with lemon or vinegar to prevent from discoloring as you would do with artichoke.
Rutabagas are part of the Brassica napus family and originated as a cross between cabbage and turnip. These yellow and purple delights are used much like turnips and should be peeled. When roasted with other root vegetables, such as celery root and parsnips, sweet, young turnips or Brassica rapus add balance. The smaller, tender skinned turnips do not need to be peeled and only require a thorough scrubbing (and their greens are wonderful sauteed). Larger, thicker-skinned turnips need to be peeled.
Parsnips look like pale, wide carrots and can be pureed, roasted, or sauteed to a crisp. Lightly peel the outside before using. They are often pureed and combined with potatoes and other root vegetables. Parsnips are high in fiber, potassium, and vitamin C.
A root vegetable gratin is a great way to become better acquainted with the intriguing fall and winter root vegetables. In this rich and creamy root vegetable gratin I used yukon gold potatoes and baby white turnips from the CSA box and rutabaga, parsnip, and celery root from the farmer's market. If you layer the vegetables separately, you can taste the remarkable flavors of each of the root vegetables individually. The gratin comes together with nutty parmesan, cream, garlic, fresh thyme, fennel fronds (or parsley) and a touch of nutmeg. This is hands down the best preparation of root vegetables that I have ever tasted!
Root Vegetable Gratin
5 small potatoes, peeled
1/2 of a large celery root, top and bottom removed and peeled
1/2 of a medium parsnip, peeled and cored
2 to 3 small baby white turnips
2 small rutabagas, peeled
1 1/4 cup heavy cream or whole milk
pinch of nutmeg
1 cup + freshly grated parmesan
4 cloves garlic, minced1 tbsp thyme
optional 1 tbsp fennel fronds or parsley
sea salt and freshly ground black pepperPreheat oven to 425F. Butter a 9 by 13 gratin dish.
Slice the potatoes on a mandoline into 1/16" thick slices. Repeat with each of the root vegetables, keeping them separate.
Stir garlic, nutmeg, fresh thyme, and fennel fronds into the heavy cream. Season with salt and pepper.
Arrange potato slices in overlapping rows on the bottom of the gratin dish. Sprinkle with salt and pepper. Add a layer of rutabaga, sprinkle with salt and pepper, then add a layer of celery root and seasoning again. Repeat with a layer of parsnip and then turnip, seasoning in between each layer. Sprinkle with half of the parmesan. Repeat starting with a layer of potatoes, seasoning between each layer. Finally, top with a final layer of overlapping potatoes. Pour the milk mixture over the top until it comes to the edge of the top layer. Press the vegetables down into the milk with a spatula.
Cover with foil and bake for about 1 hour. Remove the foil and lightly press the gratin down with a spatula. Sprinkle with remaining parmesan and continue baking until the vegetables are tender the top is golden brown, 15 to 30 minutes more. Remove from the oven and let stand for 15 minutes before serving.