What could be better than a rich and creamy bowl of mashed potatoes? How about a bowl of mashed potatoes infused with celery and horseradish? This fluffy bowl piles on the roots, with celery root and horseradish joining the mix. The result is a delicious side of potatoes, with an extra dimension of fragrance, flavor, and bite. Celery root, also known as celeriac, is the dark horse of root vegetables. Don’t let its gnarly, bulbous exterior put you off. Once you cut away the skin, a milky white interior is revealed, softly redolent with celery. Celery root can be eaten raw and grated into salads, and when cooked, it’s a non-starchy alternative or complement to potatoes in mashes, gratins, and soups. Horseradish is also a root and belongs to the mustard family, which explains its peppery bite. Horseradish is often grated raw and folded into sauces and garnished over meats. …