3 cups milk
3 cups water
1 Tbsp salt
1 kg celery roots, peeled, cut into 2-inch cubes
1 medium potato, peeled, cut into 2-inch cubes
1 small onion, peeled, quartered
5 Tbsp butter and/or olive oil
ground white pepper
chopped fresh chives
Bring milk, water, and salt just to boil in heavy large saucepan over high heat. Add celery root cubes, potato cubes, and onion quarters; bring to boil. Reduce heat and simmer until vegetables are tender, about 30 minutes. Drain, discarding cooking liquid.
Combine vegetables and butter in processor and puree until smooth. Season to taste with salt and white pepper. Sprinkle with chopped fresh chives and serve.
Note: Celery root puree can be made 1 day ahead.
Adapted from Epicurious.com