Black radishes may not be the biggest, brightest item on winter markets in Brittany, but nearly every vegetable stand has a small pile of bent, misshapen dark roots with short frills of remaining stems—and nearly every week I pick up a couple. Unpeeled and thinly sliced, black radishes shed any homeliness and take on a dramatic beauty with their snow white centers and pitch-dark skin. Their bite is sharper than daikons or the red vegetables of spring or and they’re lauded as a liver-cleansing, detox remedy for winter.
I mostly eat black radishes as a snack or use them in place of crackers for dips and hors d’oeuvres. Sometimes though, I’ll pick up one with a flavor that’s a little too fiery to enjoy raw. Then, I make radish soup. And oh, what a soup it is! Deliciously, unapologetically radishy with a stunning absence of color, it’s is both satisfyingly homey and gorgeously elegant. Come spring, I make the same recipe with red radishes which turn the soup an equally beautiful cherry-blossom pink. In summer, I serve that pink radish soup cold like a gazpacho. I’ve even used it to turn a limp daikon radish that got lost in the back of the fridge into something edible. In other words: this is a soup for all seasons and all radishes, to be made even if you can’t simply grab a couple of black ones as easily as I can.
1 Tbs. unsalted butter or olive oil
1 medium white onion, chopped
2 medium black radishes, peeled or 3 cups red radishes (about 1 lb./500 g.) radishes, halved (3 cups), plus more (unpeeled) for the garnish
1 medium russet potato, peeled and cut into chunks
¼ tsp. salt
1/8 tsp. white pepper
1 Tbs. prepared horseradish sauce
2 Tbs. crème fraîche, plus more for garnish, optional
Heat the butter in a medium saucepan over medium heat. Add the onion, and sauté 5 minutes, or until soft and translucent.
Add the radishes, potato, salt, pepper, and 3 1/2 cups water. Bring the soup to a boil, reduce heat to medium-low, and simmer, covered, 30 minutes.
Remove the soup from the heat, stir in the horseradish, and purée in a food processor or with an immersion blender until smooth. Add the crème fraîche, if using, and purée until combined. Adjust seasonings, and serve topped with grated radish. Makes about 6 cups