Place potatoes and garlic in large saucepan; pour in enough water to cover potatoes. Set pan over high heat and bring to a boil; boil until potatoes are fork-tender, about 8 minutes.
2
Drain potatoes and garlic; transfer potatoes and garlic to a large bowl. Add yogurt and sugar to bowl; mash until smooth. Season to taste with salt and pepper. Yields about 1/2 cup per serving.