Celery Root, Kohlrabi & Apple Puree
- 2 pounds celery root (celeriac), peeled, cut into 3/4" cubes
- Kosher salt
- 1 1/2 pounds kohlrabi, peeled, cut into 1/2" cubes
- 1 pound russet potatoes, peeled, cut into 1" cubes
- 1 Granny Smith apple (1/2 pound), peeled, cored, cut into 1" cubes
- 2 tablespoons (1/4 stick) unsalted butter
- Freshly ground black pepper
- Fresh chervil sprigs
Add celery root to a large pot of boiling salted water. Reduce heat to medium-low and simmer until tender, 11-13 minutes. Using a slotted spoon, transfer celery root to a large bowl. Return water to a boil; repeat with kohlrabi, then potatoes, cooking each separately until tender, 14-16 minutes for kohlrabi and 10-12 minutes for potatoes; add to bowl with celery root.
Meanwhile, bring apple and 2 tablespoons water to a boil in a small saucepan. Cover and cook over medium-high heat, stirring occasionally, until apple falls apart, 6-8 minutes, adding water by tablespoonfuls if dry. Working in batches, pass celery root, kohlrabi, potatoes, and apple through a potato ricer into a large bowl. Pass mixture through ricer again if a smoother texture is desired. Stir in butter. Season with salt and pepper.