Using largest holes on box grater, shred potatoes into large bowl. Mix in egg and next 4 ingredients. Transfer potato mixture to strainer set over same bowl. Add enough oil to heavy medium skillet to reach depth of 1/4 inch. Heat oil over medium-high heat. Working in batches, drop batter by rounded tablespoonfuls into hot oil, flattening with back of spoon to form 2- to 3-inch-diameter 1/4-inch-thick pancakes. Fry until golden brown, about 4 minutes per side. Transfer pancakes to paper towels to drain. Top pancakes with crème fraîche, red onion, and caviar; serve. *Available at some supermarkets and at specialty foods stores.