Celery Root and Potato Gratin is a great autumn side dish. Celery root, aka celeriac, is one of the unsung root vegetable heroes. Its ugly, gnarly outside can be rather off-putting, but its strong... peppery ‘celery’ taste is worth being brave for. Celery root is a flavorful alternative for bland potatoes and is full of nutritious vitamins and minerals. We love it for a change with Roast Chicken or with the Holiday Turkey.
Cut off the gnarly top and the bottom of the celery root knob. Peel, rinse, scrub it well to remove any remaining dirt. Halve the knob and cut into about a ½-inch cube.
Put the diced celery root into a saucepan and cover with cold water. Bring to a boil. Add ½ teaspoon of salt. After the celeriac has been boiling for about 5 minutes, add the cubed potato. Cook until the potatoes and celery root are tender. Drain, reserving ½ cup of the cooking water.
In the same saucepan or large bowl add to the potatoes and celery root all the yogurt and ½ the butter or oil if using, . Mash until a soft puree is formed. Add a little of the reserved cooking water if it seems too stiff. Taste for salt and add a grind or two of black pepper.
Spoon the mash into a baking dish and flatten the top with a fork, making decorative patterns with a fork.
Dot with the remaining oil or butter if using and bake for 20 minutes or until well browned.
If you want to make this vegan, instead of yogurt use 2 tablespoons silken tofu blended with 1 teaspoon olive oil, a pinch of salt, and 1/2 teaspoon of either lemon juice or umeboshi paste to add a little sourness to the tofu.
If you have any left overs, rub a non-stick pan with a little olive oil or butter, and gently fry the left overs into a potato cake to eat with eggs or another protein like grilled chicken or fish.
Celeriac is nutrient rich in minerals like manganese, phosphate, iron, and copper, and in vitamins C & B6.