Celery root and sorghum gratin recipe

Ingredients

• ½ cup sorghum
• 1 (2-pound) celery root
• 2 tablespoons unsalted butter, plus more for greasing the pan
• 6 scallions, white and light green parts only, minced
• 2 tablespoons whole wheat flour or whole wheat pastry flour
• 1½ cups milk (whole, 2%, 1%, or even fat-free), divided
• ½ cup dry white wine or dry vermouth
• 2 ounces Gruyère, shredded
• 1 teaspoon ground black pepper

1. Soak the sorghum in a big bowl of cool water for at least 8 and up to 16 hours. Drain it in a fine-mesh sieve or small-holed colander set in the sink. Pour the grains into a large saucepan, swamp it with plenty of water, and bring to a boil over high heat. Reduce the heat to low and cook until fairly tender, about 1 hour 45 minutes. Sorghum will retain a grainy, starchy texture, even when fully cooked; however, the individual grains should still be tender to the bite.
2. Meanwhile, peel the celery root. Sounds easy but isn’t. Use a vegetable peeler to get off some of the tough, outside bits, then switch to a paring knife to get off the last of the peel as well as any hairy roots in the pits and cracks. Cut the big knob into quarters, then cut these into 1⁄8-inch-thick slices. You can do that in several ways: with a food processor and a 1⁄8-inch slicing blade, with a mandoline set for 1⁄8-inch slices, or with a very sharp chef’s knife.
3. Bring a second large saucepan of water to a boil over high heat. Add the celery root slices and blanch them for 5 minutes. (Don’t want to dirty another pot? You can add them to the bubbling water in the sorghum pot, but you’ll have to work in batches and you’ll need a slotted spoon to get them out without disturbing the cooking grains. Maybe two pots isn’t so much trouble after all.) Drain the celery root slices in a colander set in the sink; run under cool water.
4. Dump the celery root slices out of the colander and onto a cutting board, then drain the sorghum in that colander set in the sink. Now you’re ready to make the gratin.
5. Position the rack in the center of the oven and preheat to 400°F. Lightly butter a 9 x 13-inch baking dish.
6. Melt 2 tablespoons butter in a large skillet over medium heat, then add the scallions. Cook just until wilted a bit, about 1 minute, stirring all the while. Stir in the flour, coating the scallions as they continue to cook.
7. Whisk in 1 cup of the milk in a slow, steady stream. Since you’re working with whole wheat flour, you’ll need to pour the milk in more slowly and whisk more in line with the courage of your whole-grain convictions. Continue whisking until thickened and bubbling, then whisk in the wine or vermouth as well as the Gruyère. Remove the skillet from the heat.
8. Layer one-third of the celery root pieces in the prepared baking dish, overlapping the slices as necessary to make sure the bottom is fully covered. Spread one-third of the sauce over these slices, then sprinkle with half the sorghum. Now repeat the layering: half the remaining celery root slices, half the remaining sauce, and all of the remaining sorghum. Finally, layer the remaining celery root slices on top and shellac the whole thing with the remaining sauce. Pour the remaining ½ cup milk over the casserole and sprinkle it with the pepper.
9. Bake until golden brown and bubbling at the edges, about 45 minutes. Cool on a rack for 10 minutes before cutting the casserole into gooey squares or rectangles to serve.