I admit that when my husband spied this dish on our Meatless Monday dinner table, he appeared skeptical. "But you love celery root, potatoes and beer," I implored. "This will be great." After one bite, he had joined my team, and I admit that we finished the entire bowl. For most folks, this would probably serve 4 as a side dish, but as a main, it fed the two of us in a very satisfying way. Also, it's easy as can be!
The flavors are wonderfully complementary and while the mash can surely stand on its own, the beer reduction adds a very cool element and a nice color contrast. Also, who wouldn't like beer gravy? ;) —em-i-lis
Test Kitchen Notes
This is an alternative to traditional mash that's easy enough for a weeknight but dressy enough to grace the holiday table, and the sauce makes this a standout from the usual alternate mashes. The caramelized leeks and garlic balance the brightness of celeriac and potato skins well. I stuck with the Negra Modela suggestion, but craft brew enthusiasts might try Old Rasputin or a similar dark beer. The reduction smells a little acrid at first, but mellows nicely at the ten-minute mark. I served this with a fried egg and a side of chard, but this would pair nicely with red meats or gamier fowl, too. —EAng
For the roasted veggies and mash:
Medium-large celery root, peeled, trimmed and cut into 3/4" cubes
Medium leek, trimmed, washed well, halved lengthwise and then crosswise
Small, thin-skinned gold potatoes, washed, left unpeeled, chopped into 3/4" cubes
Large cloves garlic, left in their skins
Extra-virgin olive oil, sea salt, freshly ground black pepper
Preheat oven to 385°F. In a medium-large mixing bowl, put the chopped celery root, potatoes and leek, garlic cloves and thyme. Pour several tablespoons of olive oil in and sprinkle generously with fine sea salt and several good grinds of black pepper. Gently toss everything together until coated and turn out onto a baking sheet.
Roast until the potatoes and celery root give no resistance when pierced with a knife, at least 20 minutes. When done, carefully remove the baking sheet from the oven and let cool until you can slip the garlic cloves from their skins. Discard the skins and the thyme sprigs, and transfer everything else to a food processor.
With the motor running and the veggies processing, pour the buttermilk through the feeding tube, adding more if you want. I like my mash to retain a slightly chunky texture so don't go for full purée. Season to taste with more salt and pepper and turn out into a serving bowl. Keep warm if you're going to eat the mash soon; otherwise, cover and rewarm before serving.
For the beer-molasses reduction:
While your veggies are roasting, whisk together the beer and molasses in a skillet set over medium-high heat. Bring to a good simmer and cook until reduced to a generous 1/8 cup, whisking occasionally. This will probably take 20 minutes or so. When reduced, pour into a glass vessel and immediately whisk in the brown sugar until dissolved. Drizzle over the warm veggie mash and jump in.