This gratin is rich with aroma and flavor. It’s great for dinner served with a mixed green salad topped with roasted red peppers and olives.
3 medium red potatoes, sliced 1/4-inch thick
1 large celeriac, peeled, cut into quarters, and sliced 1/4-inch thick
1 tablespoon olive oil
1 medium red onion quartered, and sliced (or sweet white onion)
2 cloves garlic, minced
2 small celery stalks, chopped
1 tablespoon chopped fresh basil
1 cup dry white wine (or vegetable broth)
1 15-ounce can whole tomatoes, chopped, juices reserved
Bring a large pot of water to a boil. Add salt to taste to boiling water, then add potatoes and cook until just tender, about 5 minutes. Using a slotted spoon, remove potatoes to a bowl, then add celery root to boiling water and cook until just tender, about 4 minutes. Using a slotted spoon, remove celery root to bowl with potatoes. Reserve cooking liquid.
In medium skillet, heat oil over medium heat. Add onion, garlic, celery and basil and season to taste with salt and pepper. Cook, stirring often, until softened, about 5 minutes. Add wine, increase heat and cook to reduce wine by half, about 5 to 7 minutes. Add tomatoes and their juices plus 1/2 cup of reserved cooking liquid.
Preheat oven to 375 degrees F. Grease a 2-quart baking dish. Ladle half of the tomato mixture in bottom of prepared pan. Make a layer of alternating potato and celery root slices, season to taste with pepper. Repeat, using remaining potato and celery root slices. Cover with remaining tomato mixture. Cover and bake until potatoes and celery root are tender, about 45 minutes. Remove gratin from oven and let stand 10 minutes before serving. Serve warm.