1 large garlic clove, sliced
3 Tbsp Olive Oil
1 Tbsp fresh sage leaves, minced or 1 tsp Ground Sage
For fried sage leaves:
Olive Oil for frying
12 whole fresh sage leaves
Coarse Salt for sprinkling
4 russet (baking) potatoes (about 2 pounds)
1 Cup plain yogurt
1 Tbsp unsalted butter, softened
In a small saucepan, saute garlic in olive oil until golden. Stir in sage, and remove pan from heat. Let mixture stand 15 minutes, and drain the oil through a fine sieve into a small bowl, discarding solids.
Make fried sage leaves:
In a small skillet, heat 1/8 inch oil over moderately high heat until hot but not smoking, and fry sage leaves, 1 at a time, about 3 seconds each, until crisp. Using a slotted spoon, transfer each sage leaf to paper towels to drain. Sprinkle sage leaves with coarse salt.
Peel potatoes and quarter. In a large saucepan, cover potatoes by 1 inch with salted cold water. Bring water to a boil, then reduce to a simmer; cook until tender, about 20 minutes. Reserve about 1/3 cup cooking liquid and drain potatoes.
Preheat oven to 350°F.
While potatoes are still warm, force them through a potato ricer or using medium disk of a food mill, smoosh cooked potatoes into a bowl. Beat in yogurt, butter, garlic-sage seasoned oil, and enough reserved potato-cooking liquid for the potatoes to reach desired consistency. Add salt and pepper to taste.
Transfer potatoes to an ovenproof serving dish. Mashed potatoes may be made up to 1 day ahead and chilled, covered.
Heat potatoes in oven until heated through and top with fried sage leaves.