CELERIAC
Celeriac is the white part of the special form of celery (Apium graveolens) and is also known as celery root or knob celery. It is different from the ordinary celery, since just the root is eaten and the leaves are thrown away. It doesn't have the well-developed stem or leaves that the usual celery stalks possess. Celeriac is a perfect flavoring ingredient in soups, stocks, stews, and other dishes, and it can also be used in salads and in drinks like Bloody Mary (where the stalk is used). Since its main flavor molecule is the same as in celery, celeriac reminds of celery, but it also has a touch of parsley flavor, and it comes in a different shape. The most popular use of celeriac is in Europe, where it is often cooked alongside other root vegetables. The western side of the planet seem to have found more use of celery, but the celeriac is still a nicely textured and appealing vegetable once you get it clean and cut into nice shapes. It is indeed surprising that celeriac is so forgotten in the kitchens these days, because its flavor and half-crispy texture are really something to cling to. Maybe the neglectance is due to its odd looks?
Preparation of celeriac is simple. Just peel the skin and remove any threads and lumps, so that the entire surface of it is white and clean. Use paring knife to do that: just shave down the skin in broad cuts, since the rootlets often go deep into the inner part of celeriac. Then, just cut it into pieces of the desired size and put them into acidulated water to prevent discoloration (unless you use them directly). You can use cooked celeriac for purée, maybe together with other root vegetables, e.g. carrots and potatoes. You can also eat celeriac raw, on its own or use it in salads together with other aromatic veggies. A popular French celeriac salad is called celerie remoulade, in which the celeriac pieces are blanched briefly lemon juice water (to get rid of the raw-tasting feel) and then put on a plate and garnished with a mustard mayonnaise.
A simple recipe to let you test the real power of celeriac: French fries. In a pot, put some water and juice of a half lemon and put on the hot stove to bring to the boil. Meanwhile, peel the celeriac, making sure that every rootlet and thread is removed and it looks all white and clean. Then cut the celeriac into smaller pieces, just like a French fried potato. Immediately add the celeriac to the acidulated boiling water and let it blanch for about 5 minutes. Remove from the heat and drain the water on a paper towel. In a pot, heat up some oil and throw in the parboiled celeriac into it. Fry it until it becomes lightly browned, then put on a paper towel to drain the fat. Season with salt and pepper and serve at once. This makes a good side dish and alternative for the usual French fries.
Celeriac is good with potatoes and other root vegetables. It is a standard in mirepoix unless you use the celery stalks. Try to mix it with garlic, mustard, butter or butter sauces, some herbs, and maybe some cream. Just a light seasoning makes it a very interesting vegetable to work with.
Nutritionally, celeriac is low on calories and it contains low amount of sugars. It also has a low starch content, but carries a good amount of dietary fibers.
Celeriac should be stored in a refrigerator, where it usually keeps for a few months. The best season is the cold part of the year, that is, fall and winter.