- 1 pound russet potatoes, peeled and sliced 1 1/2 inches thick
- 1 pound celeriac, peeled and sliced 1 1/2 inches thick
- Coarse salt
- 1/2 cup sour cream
- 2 tablespoons unsalted butter
- 1/4 teaspoon freshly ground nutmeg
- Freshly ground pepper
- Place potatoes and celeriac in a medium saucepan, and fill with enough cold water to cover by about 2 inches. Bring to a boil over high heat; add salt generously. Reduce heat to a simmer, and cook until vegetables are tender when pierced with a paring knife, 20 to 25 minutes. Drain in a colander.
- Pass potatoes and celeriac through a ricer or food mill into a serving bowl. Add sour cream and butter, and stir until combined. Stir in nutmeg, and season with salt and pepper. Serve immediately.