1 Idaho® potato, about 12 ounces, peeled and quartered
3/8 cup whole blanched almonds
2 to 3 cloves garlic, roughly chopped
1 1/2 teaspoons freshly squeezed lemon juice
1/4 cup extra-virgin olive oil
Salt and black pepper, to taste
Cut both ends of celery root so it stands on a cutting board; peel in a spiral pattern with a sharp knife or peeler; rinse to remove any dirt; cut into eighths. Place pieces in medium saucepan; cover with warm water and 1/2 teaspoon salt. Bring to boil; reduce to a simmer. Cook until fork-tender, 20 to 25 minutes. Drain, reserving 1 cup of cooking water.
While celery root is still hot, combine in food processor with yogurt and 1/4 cup of reserved cooking liquid. Purée with metal blade until smooth and creamy. Transfer purée to medium mixing bowl; reserve.
Place potato quarters in medium saucepan with water to cover and 1 1/2 teaspoons salt. Bring to boil over high heat. Reduce heat to medium; simmer until tender, 15 to 18 minutes; drain. While potatoes are still hot, press through a ricer or food mill. Fold potatoes into celery root mixture.
Combine almonds, garlic, remaining 3/4 cup reserved cooking liquid, lemon juice, olive oil and remaining 1 teaspoon salt in a blender. Blend until completely smooth and creamy, about 2 minutes.
Fold nut mixture into potato/celery-root mixture. Season to taste with salt and black pepper.
Serve at room temperature or cold, as an appetizer or hors d?oeuvre. This dish pairs well with grilled bread, grilled beef kebabs or skewers of marinated, grilled mushrooms.