- 3 tablespoons plus 2 teaspoons extra-virgin olive oil plus more for drizzling
- 6 small celery roots (celeriac; each about 4 ounces), unpeeled, trimmed with some stem still attached
- 1/2 cup (1 stick) unsalted butter, cut into 1″ cubes
- Kosher salt
- 12 sprigs thyme
- 6 sprigs rosemary
- 6 sprigs sage
- 1 tablespoon coffee beans (optional)
- 1 cup buttermilk
- 1/2 lemon
- 1/4 cup oil-cured black olives, pitted, quartered lengthwise
- Heat 3 tablespoons oil in a large heavy pot over medium heat. Add celery roots and cook, turning frequently, until golden, 8-10 minutes. Add butter and a large pinch of salt. When butter begins to foam, reduce heat to medium-low. Add herb sprigs, coffee beans, if using, and 1 1/2 cups water. Cover and gently cook, adding more water by tablespoonfuls if pan is dry, until celery roots are very tender, about 1 hour.
- Remove herbs and coffee beans (if using) from pot and discard. Baste celery roots with buttery juices in pot. Remove from heat. Transfer celery roots to a cutting board, slice in half through stems, and place 2 halves on each plate.
- Meanwhile, very gently warm buttermilk in a small saucepan over low heat (it will break if warmed too much). Squeeze in a few drops of lemon juice and add remaining 2 teaspoons oil and a pinch of salt to make a loose sauce. Spoon sauce around celery roots on plates. Garnish with olives, drizzle with oil, and squeeze a few more drops of lemon juice over each.