Mix the crème légère and horseradish. Wash the tomato, grate dry and cut into slices. Clean the salad, wash and shake dry. Toast bread. Spread horseradish cream on the bread.
Halve the roast beef slice and roll it up. Cover 1 slice of bread with salad, tomatoes and roast beef. Place 2nd slice of toast on top and fix with toothpicks. Cut the bread diagonally in half.