How to Make It
In a food processor or on a box grater, coarsely grate the sweet potato. In a large bowl, combine the matzo meal with the sugar, flour, salt, baking powder, cayenne and pepper. Stir in the egg, egg white and milk. Stir in the sweet potato.
In a medium skillet, heat 2 tablespoons of vegetable oil until shimmering. Drop packed teaspoons of the sweet potato mixture into the skillet and flatten them with the back of a spoon. Cook the latkes over moderately high heat until the edges are golden, about 1 1/2 minutes; flip and cook until golden on the bottom, about 1 minute. Drain on paper towels. Repeat with the remaining sweet potato mixture, adding more oil as needed.
In a small bowl, mix the crème fraîche with the wasabi paste, rice vinegar and salt. Arrange the latkes on a platter and top each one with the wasabi cream, a pinch of sprouts and a little tobiko. Serve warm.
Wasabi tobiko (wasabi-flavored flying fish roe) is available from Wild Edibles (877-295-3474 or wildedibles.com).